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1

Evaluation of Flexible Pavement Performance Life in Florida.  

National Technical Information Service (NTIS)

The pavement performance life provides information on how long a particular pavement type will typically last before it needs rehabilitation. This study presents the research effort to estimate the average flexible pavement performance life in Florida. Tw...

W. V. Ping Y. He

1998-01-01

2

Flexible pavement performance evaluation using deflection criteria  

Microsoft Academic Search

Flexible pavement projects in Nebraska were monitored for dynamic deflections, roughness, and distress for six consecutive years. Present surface conditions were characterized and data for evaluating rehabilitation needs, including amount of overlay, were provided. Data were evaluated and factors were isolated for determining the structural adequacy of flexible pavements, evaluating existing pavement strength and soil subgrade conditions, and determining overlay

R. J. Wedner

1980-01-01

3

Flexible pavement performance evaluation using deflection criteria  

NASA Astrophysics Data System (ADS)

Flexible pavement projects in Nebraska were monitored for dynamic deflections, roughness, and distress for six consecutive years. Present surface conditions were characterized and data for evaluating rehabilitation needs, including amount of overlay, were provided. Data were evaluated and factors were isolated for determining the structural adequacy of flexible pavements, evaluating existing pavement strength and soil subgrade conditions, and determining overlay thickness requirements. Terms for evaluating structural condition for pavement sufficiently ratings were developed and existing soil support value and subgrade strength province maps were evaluated.

Wedner, R. J.

1980-04-01

4

Parametric Study of Factors Affecting Flexible-Pavement Performance  

Microsoft Academic Search

A new 'Whole-Life' Pavement Performance Model (WLPPM) that is capable of making deterministic pavement damage predictions due to realistic traffic and environmental loading has been developed. A vehicle simulation is used to generate dynamic tire forces that are a function of distance along the pavement. These dynamic tire forces are then combined with the appropriate pavement primary response influence functions

A. C. Collop; D. Cebon

1995-01-01

5

A model of whole?life flexible pavement performance  

Microsoft Academic Search

A new 'whole-life' pavement performance model (WLPPM), that is capable of making deterministic pavement damage predictions due to realistic traffic and environmental loading, has been developed. A vehicle simulation is used to generate dynamic tyre forces that are a function of distance along the road. These dynamic tyre forces are then combined with the appropriate pavement primary response influence functions

A. C. Collop; D. Cebon

1995-01-01

6

Multiscale Assessment of Low-Temperature Performance of Flexible Pavements  

Microsoft Academic Search

The increase of heavy-load traffic within Europe requires the development of appropriate tools for the assessment of existing\\u000a and new road infrastructure. In this paper, such a tool is presented, combining multiscale material modeling of asphalt with\\u000a structural analysis of flexible pavements representing plate-like structures at low temperatures. At this temperature regime,\\u000a rapid cooling of the road surface in consequence

E. Aigner; R. Lackner; M. Spiegl; M. Wistuba; R. Blab; H. Mang

7

Effect of Drainage in Unbound Aggregate Bases on Flexible Pavement Performance.  

National Technical Information Service (NTIS)

It has been well demonstrated that a positive subsurface drainage is beneficial in enhancing pavement performance and thus extending pavement service life. Typical permeable base materials include asphalt/cement-treated, open-graded aggregates and unbound...

M. Tao M. Y. Abu-Farsakh

2008-01-01

8

Analysis of Flexible Pavements Reinforced with Geogrids  

Microsoft Academic Search

Effectiveness of glass fiber grids as a reinforcement of the asphalt layer in a flexible pavement system was investigated.\\u000a The study involved both laboratory experimental work and computer analysis of pavement sections. Twenty flexible pavement\\u000a sections (with and without glass fiber grids) were constructed and tested in the laboratory as a part of the experimental\\u000a study. The laboratory-scale pavement sections

Hema Siriwardane; Raj Gondle; Bora Kutuk

2010-01-01

9

Finite element modelling of flexible pavements on soft soil subgrades  

Microsoft Academic Search

The effect of tyre pressure, wheel configuration and axle load variations of a transportation truck, on structural performance of a flexible road pavement with thin asphalt surfacing layer and soft peat soil subgrade was evaluated using the finite element method. The pavement structure was modelled as two-dimensional four-layer stratum using ANSYS\\/ED finite element suite. The pavement model was subjected to

R. M. Mulungye; P. M. O. Owende; K. Mellon

2007-01-01

10

Evaluation of superheavy load movement on flexible pavements  

Microsoft Academic Search

Due to industrial plant expansion, superheavy load moves have increased drastically in Louisiana within the past decade. This paper presents a case study of a superheavy load movement with over 1.8-million kg loads on a flexible pavement. The study included pavement structural analysis under superheavy load and the estimation of cost attributable to the movement. The structural evaluation was performed

Xingwei Chen; Jeffrey R. Lambert; Ching Tsai; Zhongjie Zhang

2012-01-01

11

Long-Term Performance of Stone Interlayer Pavement  

Microsoft Academic Search

This paper presents an evaluation of long-term performance of an alternative flexible pavement design referred to here as stone interlayer pavement. This pavement design was introduced to reduce\\/defer reflective cracking experienced with soil-cement bases. The stone interlayer pavement consisted of a crushed limestone base on top of a cement-stabilized base. The performance of the stone interlayer pavement was compared to

Hani Titi; Masood Rasoulian; Mark Martinez; Byron Becnel; Gary Keel

2003-01-01

12

Investigation of Premature Distresses in Flexible Pavements.  

National Technical Information Service (NTIS)

The study was undertaken to investigate the growing concern regarding premature distresses in flexible pavements in North Carolina and to identify the causes and mechanisms associated with these untimely failures. This objective was approached through ext...

N. P. Khosla

1985-01-01

13

Flexible and Composite Structures for Premium Pavements. Volume 2. Design Manual.  

National Technical Information Service (NTIS)

The design manual presents the results of a detailed study to identify and design flexible and composite pavement configurations which will perform as premium or 'zero-maintenance' pavements. The manual includes identification and classification of the pa...

H. L. von Quintus F. N. Finn W. R. Hudson F. L. Roberts

1980-01-01

14

Mechanistic design concepts for conventional flexible pavements  

NASA Astrophysics Data System (ADS)

Mechanical design concepts for convetional flexible pavement (asphalt concrete (AC) surface plus granular base/subbase) for highways are proposed and validated. The procedure is based on ILLI-PAVE, a stress dependent finite element computer program, coupled with appropriate transfer functions. Two design criteria are considered: AC flexural fatigue cracking and subgrade rutting. Algorithms were developed relating pavement response parameters (stresses, strains, deflections) to AC thickness, AC moduli, granular layer thickness, and subgrade moduli. Extensive analyses of the AASHO Road Test flexible pavement data are presented supporting the validity of the proposed concepts.

Elliott, R. P.; Thompson, M. R.

1985-02-01

15

Effects of temperature and water on pavement performance  

SciTech Connect

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

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

1987-01-01

16

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

17

Geogrid mechanism in low-volume flexible pavements: accelerated testing of full-scale heavily instrumented pavement sections  

Microsoft Academic Search

This study uses full-scale accelerated testing to provide new insight into the effectiveness of geogrids on the performance of low-volume flexible pavements. Although several previous studies reported that geogrids improve pavement performance by enhancing its structural capacity and reducing distress potential, this study goes further to quantify the effectiveness of geogrids, specify the mechanism of the reinforcement they provide and

Imad L. Al-Qadi; Samer Dessouky; Erol Tutumluer; Jayhyun Kwon

2011-01-01

18

Pavement performance equations. Final report  

SciTech Connect

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 data rather well given the expected variation of pavement performance information. The relative effects of age (time since construction or reconstruction) were illustrated for the three surface types.

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

1988-03-01

19

Non-linear finite element analysis of flexible pavements  

Microsoft Academic Search

A research study is being undertaken to incorporate the realistic material properties of the pavement layers and the moving traffic load, in the analysis of flexible pavements, using the finite element theory. As a preliminary step taken herein in this direction, a pavement structure where field measurements have been carried out when subjected to a cyclic loading, is selected and

Muhammad N. S. Hadi; B. C. Bodhinayake

2003-01-01

20

Structural response of LVR flexible pavements at Mn/ROAD project  

SciTech Connect

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

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

1999-05-01

21

Finite Element Simulation of Structural Performance on Flexible Pavements with Stabilized Base/Treated Subbase Materials under Accelerated Loading.  

National Technical Information Service (NTIS)

Accelerated pavement testing (APT) has been increasingly used by state highway agencies in recent years for evaluating pavement structures and/or materials. However, running an APT experiment is expensive. It requires costly accelerated loading devices an...

X. Chen X. Yang Z. Wu

2011-01-01

22

Evaluation of flexible pavement crack sealing methods used in Utah  

NASA Astrophysics Data System (ADS)

Criteria to improve the effectiveness of Utah's flexible pavements crack sealing practice were studied. Field measurements, in-depth interviews questionaires were used. Findings indicate that flexible pavement cracking is a significant problem in the Far West, Rocky Mountains, Great Lakes and New England. Choice of materials is effected by storage requirements and equipment available. Prepackaging of materials designed for crack sealing has resulted in improvements in control of mix and material properties. Low temperature and freeze thaw cycles significantly effect the amount of thermal cracking and the performance of crack sealant. Ductile sealants, such as Crumb rubber/asphalt cement mixes, in combination with routing appear to offer substantial gains in sealant life and performance.

Belangie, M. C.; Anderson, D. I.

1981-01-01

23

Flexible Pavement Overlay Design by Dynamic Deflections. Phase 2.  

National Technical Information Service (NTIS)

The report summarizes a comprehensive study to develop a flexible pavement overlay design procedure based on Falling Weight Deflectometer (FWD) deflections for the South Carolina Department of Highways and Public Transportation (SCDHPT). The study include...

R. L. Baus A. M. Johnson

1992-01-01

24

FULL SCALE HIGHWAY LOAD TEST OF FLEXIBLE PAVEMENT SYSTEMS WITH GEOGRID REINFORCED BASE COURSES  

Microsoft Academic Search

The use of geosynthetics to improve the performance of flexible pave- mentshasincreasedsignificantlyoverthe last decade. Thispaper describesa full scale testing research program that used a 20 kNmoving wheel load to determine the benefit of using a stiff biaxial geogrid between the base and subgrade of a flexible pavement system. The traffic benefit ratio (TBR) was defined as the ratio of the

J. G. Collin; T. C. Kinney; X. Fu

25

Continuously Reinforced Concrete Overlays of Flexible Pavements on Trunk Road A2.  

National Technical Information Service (NTIS)

The design and construction of continuously reinforced concrete (CRC) overlays on flexible pavements of Trunk Road A2 are described. The existing pavements were dual carriageways of flexible construction built in 1975-76; isolated sections had failed comp...

J. M. Gregory

1983-01-01

26

Simplified ME Approach for the Design of Flexible Pavement Structures  

Microsoft Academic Search

This paper presents a simplified design procedure, which depends mainly on finite elements analysis considering the same input variables used in the traditional AASHTO empirical design methodology. The multiple regression equation developed considered the subgrade resilient modulus (Mr), Equivalent Single Axle Load (ESAL) repetitions, and the dynamic behavior of flexible pavements by incorporating vehicle speed. The outputs of this model

Osama Abaza

27

Predicting in-service fatigue life of flexible pavements based on accelerated pavement testing  

NASA Astrophysics Data System (ADS)

Pavement performance prediction in terms of fatigue cracking and surface rutting are essential for any mechanistically-based pavement design method. Traditionally, the estimation of the expected fatigue field performance has been based on the laboratory bending beam test. Full-scale Accelerated Pavement Testing (APT) is an alternative to laboratory testing leading to advances in practice and economic savings for the evaluation of new pavement configurations, stress level related factors, new materials and design improvements. This type of testing closely simulates field conditions; however, it does not capture actual performance because of the limited ability to address long-term phenomena. The same pavement structure may exhibit different response and performance under APT than when in-service. Actual field performance is better captured by experiments such as Federal Highway Administration's Long-Term Pavement Performance (LTPP) studies. Therefore, to fully utilize the benefits of APT, there is a need for a methodology to predict the long-term performance of in-service pavement structures from the results of APT tests that will account for such differences. Three models are generally suggested to account for the difference: shift factors, statistical and mechanistic approaches. A reliability based methodology for fatigue cracking prediction is proposed in this research, through which the three models suggested previously are combined into one general approach that builds on their individual strengths to overcome some of the shortcomings when the models are applied individually. The Bias Correction Factor (BCF) should account for all quantifiable differences between the fatigue life of the pavement site under APT and in-service conditions. In addition to the Bias Correction Factor, a marginal shifty factor, M, should be included to account for the unquantifiable differences when predicting the in-service pavement fatigue life from APT. The Bias Correction Factor represents an improvement of the currently used "shift factors" since they are more general and based on laboratory testing or computer simulation. By applying the proposed methodology, APT performance results from a structure similar to an in-service structure can be used to perform four-point bending beam tests and structural analysis to obtain an accurate estimate of the necessary Bias Correction Factor to estimate in-service performance.

Guo, Runhua

28

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

29

Application of Energy Concepts to the Performance of Airfield Pavements.  

National Technical Information Service (NTIS)

Pavement engineers have not been able to predict the performance of pavement systems prior to actual construction and operational utilization. A solution to this problem was obtained by verifying the following hypothesis developed from energy concepts: A ...

M. E. Harr W. H. Highter

1973-01-01

30

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

31

Non-linear dynamic analysis of flexible and rigid pavements  

Microsoft Academic Search

Closed form analysis is commonly used to analyze pavement structures. This type of analysis assumes linear elastic material properties and static loading conditions. In reality, pavement materials are not linear elastic materials. For example, asphalt mixtures are viscoelastic materials and cohesive soils are elastic-plastic materials. Also truck loads are moving loads. The difference between the closed form analysis assumptions and

Sameh Mohamed Zaghloul

1993-01-01

32

Evaluation of pervious concrete pavement performance in cold weather climates  

Microsoft Academic Search

Pervious concrete pavement is a sustainable and environmentally conscious paving material. Use of pervious concrete pavement in freeze–thaw climates in Canada has been minimal to date. This paper describes the performance to date of five field sites in Canada. The test areas are monitored continually, starting at the construction stage, to understand the behaviour of pervious concrete in climates in

Vimy Henderson; Susan Tighe

2011-01-01

33

Evaluation of pervious concrete pavement performance in cold weather climates  

Microsoft Academic Search

Pervious concrete pavement is a sustainable and environmentally conscious paving material. Use of pervious concrete pavement in freeze–thaw climates in Canada has been minimal to date. This paper describes the performance to date of five field sites in Canada. The test areas are monitored continually, starting at the construction stage, to understand the behaviour of pervious concrete in climates in

Vimy Henderson; Susan Tighe

2012-01-01

34

COMPARISON OF A MECHANISTIC-EMPIRICAL DESIGN MODEL TO MEASURED PERFORMANCE FOR BASE-REINFORCED PAVEMENTS  

Microsoft Academic Search

A mechanistic-em pirical design method for geosynthetic base-reinforced flexible pavements has recently been proposed, where this method shares common features with a nationally recognized mechanistic-empirical method developed for conventional unreinforced flexible pavements. The method recently developed for reinforced pavements contains components for material and damage models for the different layers of the pavement cross section, testing methods for identification of

Steve W. Perkins; Eli L. Cuelho

35

Concrete Overlay as a Rehabilitation Option for Distressed Asphalt Pavements  

Microsoft Academic Search

Ultra-thin Whitetopping (UTW) involves placing a very thin concrete overlay 50 mm to 100 mm thick (2”-4”) on the milled surface of a distressed asphalt pavement. To investigate the performance of UTW placed over a flexible pavement subjected to slow and heavy moving wheel loads, whitetopping mixes were placed over a milled pavement surface in the Accelerated Pavement Testing (APT)

Sudarshan Rajan; J. Olek

2002-01-01

36

Performance of Reclaimed Asphalt Pavement on Unpaved Roads.  

National Technical Information Service (NTIS)

The University of Wyoming's LTAP Center conducted a study examining the performance of reclaimed, recycled asphalt pavement (RAP) on unpaved roads in three Wyoming counties. Fifteen material and dust suppression treatment combinations were examined. Mater...

G. Huntington K. Ksaibati S. Koch

2011-01-01

37

STRUCTURAL EVALUATION OF FLEXIBLE PAVEMENTS USING NON DESTRUCTIVE TESTS  

Microsoft Academic Search

The aim of this paper is to contribute to the improvement of the methodologies used in structural pavement evaluation, concerning in particular the backcalculation of layer moduli based on Falling Weight Deflectometer (FWD) together with Ground Penetrating Radar (GPR) test results and using Artificial Neural Network (ANN) technique for the analysis. A brief description of the test procedures and analysis

Simona Fontul

38

Practical Construction Details Used to Build an Instrumented Flexible Pavement with Geosynthetics  

Microsoft Academic Search

A flexible pavement has been constructed over poor subgrade soil consisting primarily of highly plastic clay in northeast Arkansas (the CBR strength ranged from approximately 1-2). Seventeen instrumented test sections (each 15 m in length) have been constructed on this low volume road. In addition to the controls, test sections were reinforced with four different geotextiles, two different geogrids, and

I. L. Howard; K. A. Warren

39

Project Report on the Continued Development and Analysis of the Flexible Pavement Database.  

National Technical Information Service (NTIS)

The original scope of TxDOT Research Project 0-6275 included continuing the development of the Texas Flexible Pavement database (TFPD) developed as part of Research Project 0-5513. The objective of 0-5513 was to deliver a database capable of hosting the d...

A. Banerjee A. de F. Smit J. A. Prozzi J. P. Aguiar-Moya P. Sivarm

2012-01-01

40

Effect of Fillers on the Pavement Performance of Asphalt Binder  

Microsoft Academic Search

The effects of fillers , such as mineral fillers , cement and fibers , on the pavement performance of asphalt binder are quantitatively investigated by rheology methodology. The results show that fillers can obviously improve the high2temperature performance of asphalt binder with different degrees , and that , in the same proportion of mixture , cement has a stronger improving

Zou Gui; Yuan Yan; Zhang Xiao

2005-01-01

41

Preliminary Distress and Performance Prediction Models for Concrete Pavements in Texas.  

National Technical Information Service (NTIS)

The document presents the results of a study to develop and test distress and performance prediction models for rigid pavements (continuously reinforced concrete, jointed reinforced concrete, and jointed plain concrete pavements) in Texas. These models we...

N. Singh T. Dossey J. Weissmann W. R. Hudson

1993-01-01

42

Wide-Base Truck Tire Effects on Pavement Performance and Vehicle Regulatory Legislation.  

National Technical Information Service (NTIS)

Current operating practice in the trucking industry related to tire pressures and truck tires are summarized. Findings of recent (since 1987) pertinent pavement performance research including both full-scale and analytical pavement response and performanc...

R. K. Moore

1992-01-01

43

Performance Report on Jointed Concrete Pavement Repair Strategies in Texas.  

National Technical Information Service (NTIS)

Project 0-4517 was established to summarize the results from the Lufkin experiment on US 59 and to develop statewide guidelines on how to select rehabilitation strategies for jointed concrete pavements (JCP). This year 1 report reviews the performance of ...

C. Von-Holdt T. Scullion

2004-01-01

44

Pavement Design,  

National Technical Information Service (NTIS)

The 12 papers in the report deal with the following areas: nine-year performance evaluation of Arizona's prestressed concrete pavement; FEACONS III computer program for analysis of jointed concrete pavements; thickness design of roller-compacted concrete ...

R. L. Powers J. P. Zaniewski M. Tia J. M. Armaghani C. L. Wu

1987-01-01

45

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

NASA Astrophysics Data System (ADS)

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

Habiballah, Taha; Chazallon, Cyrille

2005-05-01

46

Effects of Temperature and Water on Pavement Performance,  

National Technical Information Service (NTIS)

The 12 papers in the report deal with the following areas: procedures for estimation of asphalt concrete pavement moduli at in situ temperatures; stress caused by temperature gradient in portland cement concrete pavements; characterizing temperature effec...

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

1987-01-01

47

Pavement management and rehabilitation of portland cement concrete pavements  

NASA Astrophysics Data System (ADS)

Pavement management and rehabilitation projects and techniques are discussed. The following topics are discussed: economic analyses and dynamic programming in resurfacing project selection; implementation of an urban pavement management system; pavement performance modeling for pavement management; illustration of pavement management: from data inventory to priority analysis; rehabilitation of concrete pavements by using portland cement concrete overlays; pavement management study: Illinois tollway pavement overlays; resurfacing of plain jointed-concrete pavements; design procedure for premium composite pavement; model study of anchored pavement; prestressed concrete overlay at O'Hare International Airport: in-service evaluation; and, bonded portland cement concrete resurfacing.

Zegeer, C. V.; Agent, K. R.; Rizenbergs, R. L.; Curtayne, P. C.; Scullion, T.; Pedigo, R. D.; Hudson, W. R.; Roberts, F. L.; Karan, M. A.; Haas, R.

48

Quantification of Smoothness Index Differences Related to Long-Term Pavement Performance Equipment Type.  

National Technical Information Service (NTIS)

The Long-Term Pavement Performance (LTPP) program was designed as a 20-year study of pavement performance. A major data collection effort at LTPP test sections is the collection of longitudinal profile data using inertial profilers. Three types of inertia...

R. W. Perera S. D. Kohn

2005-01-01

49

AN AUTONOMOUS ROBOT EQUIPPED WITH THE GPS VIRTUAL REFERENCE STATION (VRS) SYSTEM TO PERFORM PAVEMENT DISTRESS SURVEYS  

Microsoft Academic Search

Various pavement distresses (cracking, pothole, manhole, patching, etc.) that exist randomly across pavements deteriorate the quality of the pavement structure and need to be immediately dealt using proper maintenance and rehabilitation (M&R) strategies. Traditionally pavement distress surveys are performed using manually operated or driven equipment, and hence are very labour-intensive, time-consuming and lack intelligent detection methods. In this study, an

Jia-Ruey Chang; Shih-Chung Kang

50

Distress Identification Manual for the Long-Term Pavement Performance Program (Fourth Revised Edition).  

National Technical Information Service (NTIS)

Accurate, consistent, and repeatable distress evaluation surveys can be performed by using the Distress Identification Manual for the Long-Term Pavement Performance Program. Color photographs and drawings illustrate the distress found in three basic pavem...

J. S. Miller W. Y. Bellinger

2003-01-01

51

Influence of vertical load models on flexible pavement response—an investigation  

Microsoft Academic Search

This paper aims to illustrate the influence of moving loads on pavement analysis, namely their characteristics and time distribution. Firstly, a state-of-the-art load model for pavement analysis is presented. Components of traffic load (contact stresses), their magnitude and time distribution, the tyre-pavement contact area and the characterization of a moving load according to dynamic and static formulations are introduced. Secondly,

C. Vale

2008-01-01

52

Experimental estimation of the relative deterioration of flexible pavements under increased axle loads  

Microsoft Academic Search

The deterioration of Australia's unbound granular pavements with a wearing surface of stone aggregate embedded in a thin bituminous binder seal is likely to increase with increases in axle loads due to the predicted doubling of the freight task carried by heavy vehicles travelling interstate over the next 15 years. Experimental pavement deterioration data gained from accelerated load testing (ALT)

Tim Charles Martin

2011-01-01

53

Development of Field Performance Evaluation Tools and Program for Pavement Marking Materials: Technical Report.  

National Technical Information Service (NTIS)

Historically the prequalification or selection of pavement marking materials (PMMs) is mainly based on product specifications and lab testing, which do not correlate well with the field performance of the products. On the other hand, there is no consensus...

A. Pike H. Ge P. Carlson Y. Zhang

2011-01-01

54

Investigating Longevity of Corrosion Inhibitors and Performance of Deicer Products under Storage or after Pavement Application.  

National Technical Information Service (NTIS)

This study evaluated the longevity of corrosion inhibitors and the performance of inhibited deicer products under storage or after pavement application. No significant degradation of corrosion inhibitor or loss of chlorides was seen during the months of f...

A. Creighton D. Cross K. Fortune L. Fay M. Johnson M. M. Peterson R. Smithlin X. Shi Z. Yang

2011-01-01

55

Long-Term Pavement Performance Program Manual for Falling Weight Deflectometer Measurements. Version 4.1.  

National Technical Information Service (NTIS)

This document provides background information and field operations guidelines for the collection of Falling Weight Deflectometer (FWD) data on Long Term Pavement Performance (LTPP) test sections. It includes equipment setup, equipment calibration, test lo...

P. N. Schmalzer

2006-01-01

56

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

NASA Astrophysics Data System (ADS)

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

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

1998-12-01

57

Accelerated performance testing of concrete pavement with short slabs  

Microsoft Academic Search

A new concept for designing concrete pavements by optimising the slab geometry in order to reduce the slab thickness as well as to minimise the mechanical load transfer devices has recently been proposed. Theoretically, the reduced slab size lowers the load and curling-induced tensile stresses and concomitantly a thinner concrete slab can be constructed. Full-scale test sections were constructed and

Jeffery R. Roesler; Victor G. Cervantes; Armen N. Amirkhanian

2011-01-01

58

Effect of Performance Model Accuracy on Optimal Pavement Design  

Microsoft Academic Search

In the first part of this paper, an analysis of the data collected during the American Association of State Highway Officials (AASHO) Road Test, based on probabilistic duration modeling techniques, is presented. Duration techniques enable the stochastic nature of pavement failure time to be evaluated as well as censored data to be incorporated in the statistical estimation of the model

Samer Madanat; Jorge A. Prozzi; Michael Han

2002-01-01

59

Influential factors on deicing performance of electrically conductive concrete pavement  

Microsoft Academic Search

The deicing experiment of carbon fiber reinforced electrically conductive concrete (CFRC) slab was conducted in laboratory\\u000a at first, then the deicing process of CFRC pavement was analyzed by means of finite element method (FEM). At last, based on\\u000a the energy conservation law and the computing results of finite element method, the influential factors including the setting\\u000a of electric heating layer,

Tang Zuquan; Qian Jueshi; Li Zhuoqiu; Wu Chuanming

2006-01-01

60

Field application and performance of concrete overlay for pavement rehabilitation  

Microsoft Academic Search

A test section of concrete overlay was constructed and monitored for one year to evaluate the feasibility as a rehabilitation\\u000a alternative for deteriorated concrete pavement in Korea. The test section of 2-lane 290m long on 88 Highway near Jirisan I\\/C\\u000a included 25cm unbonded and 6cm and 10cm bonded concrete overlays. High early-strength slag cement was used in the overlay\\u000a concrete

Kyong-ku Yun; Young-chan Suh

1999-01-01

61

Impact of Water on the Response and Performance of a Pavement Structure in an Accelerated Test  

Microsoft Academic Search

An accelerated load test using a Heavy Vehicle Simulator (HVS) was performed with the objective of investigating the response behaviour and performance of a commonly used pavement structure in Sweden. The structure consists of 10 cm asphalt bound layers, divided into surface course and bitumen base, over granular base and subbase resting on sandy subgrade. The structure was instrumented to

Sigurdur Erlingsson

2010-01-01

62

Life Cycle, Cost, and Loading Characteristics of AASHO (American Association of State Highway Officials) Designed Rigid and Flexible Pavements in Louisiana.  

National Technical Information Service (NTIS)

The report represents a study undertaken to determine the life cycle, load characteristics, and associated costs of a representative sample of the oldest rigid and flexible pavements designed in Louisiana (1963-1967) using the AASHO Guide for Design of Pa...

W. H. Temple S. L. Cumbaa D. A. Boleware

1989-01-01

63

Application of Genetic Algorithm and Finite Element Method for backcalculating layer moduli of flexible pavements  

Microsoft Academic Search

The backcalculation program, GAPAVE, which uses the Genetic Algorithm (GA) and Finite Element Method (FEM), is developed to\\u000a predict the layer moduli from Falling Weight Deflectometer (FWD) deflections. The use of the FEM in the forward calculation\\u000a that incorporates the GA improves the accuracy in backcalculating the pavement layer moduli. The optimum GA parameters are\\u000a selected from sensitivity analysis for

Seong-Wan Park; Hee Mun Park; Jung-Joon Hwang

2010-01-01

64

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...

65

LONG-TERM IN-SITU INFILTRATION PERFORMANCE OF PERMEABLE CONCRETE BLOCK PAVEMENT  

Microsoft Academic Search

SUMMARY Since it is a design criteria for road drainage and sewer systems, the infiltration performance of permeable concrete block pavement (CBP) is of important significance during the service life of a road construction. Due to the entrainment of mineral and organic fines into the pores of porous concrete blocks or into the aggregates used in joints or openings, the

Soenke Borgwardt

66

Performance of buried flexible conduits  

Microsoft Academic Search

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 analyzed and compared with each other, and with the results of controlled experiments on small and full-scale culverts. Some relevant field measurements

G. A. Leonards; R. A. Stetkar

1978-01-01

67

Pavement evaluation and rehabilitation  

SciTech Connect

The 20 papers in this report deal with the following areas: determination of layer moduli using a falling weight deflectometer; evaluation of effect of uncrushed base layers on pavement performance; the effect of contact area shape and pressure distribution on multilayer systems response; sensitivity analysis of selected backcalculation procedures; performance of a full-scale pavement design experiment in Jamaica; subsealing and load-transfer restoration; development of a demonstration prototype expert system for concrete pavement evaluation; numerical assessment of pavement test sections; development of a distress index and rehabilitation criteria for continuously reinforced concrete pavements using discriminant analysis; a mechanistic model for thermally induced reflection cracking of portland cement concrete pavement with reinforced asphalt concrete overlay; New Mexico study of interlayers used in reflective crack control; status of the South Dakota profilometer; incorporating the effects of tread pattern in a dynamic tire excitation mechanism; external methods for evaluating shock absorbers for road-roughness measurements; factor analysis of pavement distresses for surface condition predictions; development of a utility evaluation for nondestructive-testing equipment used on asphalt-concrete pavements; estimating the life of asphalt overlays using long-term pavement performance data; present serviceability-roughness correlations using rating panel data; video image distress analysis technique for Idaho transportation department pavement-management system; acceptability of shock absorbers for road roughness-measuring trailers.

Ali, N.A.; Khosla, N.P.; Johnson, E.G.; Hicks, R.G.; Uzan, J.

1987-01-01

68

Design, Management, and Operation of Pavements.  

National Technical Information Service (NTIS)

The 5 papers in the report deal with the following areas: Pavement response and load restrictions on spring thaw-weakened flexible pavements; Use of thermistors and spring road management; Method for determining optimal blading frequency of unpaved roads;...

M. S. Rutherford Barcomb Alfelor

1989-01-01

69

Modeling deflection basin using artificial neural networks with cross-validation technique in backcalculating flexible pavement layer moduli  

Microsoft Academic Search

Through the new technological developments, for highway maintenance engineering the structural capacity of pavement is to be determined using non-destructive techniques. Up to now various methodologies have been applied based on the surface deflection bowl obtained under either a known moving wheel load or devices such as falling weight deflectometer. Backcalculating pavement layer moduli are well-accepted procedures in the evaluation

Mehmet Saltan

2008-01-01

70

Evaluation of the Performance of Cold-Mix Recycled Asphalt Concrete Pavement in Washington.  

National Technical Information Service (NTIS)

Often upgrading an aged asphalt concrete pavement involves overlaying a cracked pavement with new asphalt concrete. However, usually the substrate cracks reflect through the new overlay under repeated service loading. Full depth cold-mix recycled asphalt ...

K. Babaei J. P. Walter

1989-01-01

71

Effects of Heavy-Vehicle Characteristics on Pavement Response and Performance.  

National Technical Information Service (NTIS)

This report will be of special interest to pavement-design and pavement-management engineers, as well as the transportation planners and transportation-agency chief administrative officers responsible for funding the transportation network, allocating cos...

T. D. Gillespie S. M. Karamihas M. W. Sayers M. A. Nasim W. Hansen N. Ehsan D. Cebon

1993-01-01

72

Distress Identification Manual for the Long-Term Pavement Performance Studies.  

National Technical Information Service (NTIS)

A pictorial pavement distress identification manual that can be used to provide a uniform basis for collection of distress data on in-service highway pavement surfaces. Originally developed to provide uniform distress data for SHRP's Long-Term Pavement Pe...

1990-01-01

73

General outlook of pavement and vehicle dynamics  

SciTech Connect

The interaction between vehicle and pavement is complex since pavement roughness excites the dynamic forces generated by vehicles, while these dynamic forces simultaneously increase the pavement roughness. The objective of this paper is to provide an overview of the results of recent research related to pavement and vehicle dynamics and their interaction and to evaluate their potential use in the design and management of pavements. Pavement dynamic models are capable of determining stresses, strains, and deflections in various directions when harmonic, pulse, or transient loads are applied. Vehicle dynamic models simulate the effect of pavement roughness on the inertia of various vehicle components. These models can predict the dynamic forces produced by different axles and wheels of traveling vehicles at different locations along the pavement. Pavement response computed using dynamic models matches field measurements closer than those computed using static models. The concept of vehicle-pavement interaction can be applied to weigh-in-motion, pavement design and performance, and vehicle regulations.

Mamlouk, M.S. [Arizona State Univ., Tempe, AZ (United States). Dept. of Civil and Environmental Engineering

1997-11-01

74

Development of a Regional Pavement Performance Database for the AASHTO (American Association of State Highway and Transportation Officials) Mechnistic-Empirical Pavement Design Guide. Part 1. Sensitivity Analysis.  

National Technical Information Service (NTIS)

Optimization of transportation facilities for capacity and pavement condition could be achieved with mechanistic analysis of pavement structures. This report is focused on using the AASHTO M-E Design Guide (MEPDG) to show the results of quantitative sensi...

S. Kesiraju H. Bahia T. M. Adams

2007-01-01

75

Relationships between laboratory measured HMA material and mixture properties and pavement performance at WesTrack  

NASA Astrophysics Data System (ADS)

For years researchers and practitioners alike in the pavements and materials industry have attempted to establish relationships between laboratory measured material and mixture properties and actual pavement performance. The ultimate goal of any highway agency is to have performance related specifications, which require such relationships. This sounds simple enough, but in reality such a task is not so simple due to the extremely complex behavior of hot mix asphalt. Due to the fact that it takes many years to evaluate new materials and methodologies, the use of accelerated loading facilities such as WesTrack for evaluation purposes becomes very advantageous. The research presented here produces multiple permanent deformation performance relationships for the WesTrack project, some of which may be extended to other environments. An attempt to develop similar fatigue performance relationships was unsuccessful due partially to the lack of fatigue distress at WesTrack to date. Additionally, mix design and some quality control data summaries are presented for the project along with an investigation into a potential cause of the premature rutting of coarse Superpave mixes. The investigation resulted in the development of precision statements for the ASTM D5821-95 coarse aggregate angularity test method and a better understanding of the sensitivity of coarse Superpave mixtures.

Hand, Adam J. T.

76

Evaluation of Poisson's Ratio for Use in the Mechanistic Empirical Pavement Design Guide (MEPDG).  

National Technical Information Service (NTIS)

The pavement design industry is moving towards the use of mechanistic principles in designing flexible pavements. To determine the resultant strains in the pavement system using these principles, two material properties are required; 1) modulus and 2) Poi...

A. Maher T. Bennert

2008-01-01

77

Material characterization for studing flexible pavement behavior in fatigue and permanent deformation  

NASA Astrophysics Data System (ADS)

Mixtures' performances in fatigue and rutting were investigated. Different aggregates and gradations were studied in these mixtures. The aggregates and gradations chosen were investigated using Marshall design criteria. These aggregates were first evaluated for basic material characteristics such as specific gravity and water absorption for both fine and course fractions. Also, the Marshall stability, density and air voids contents were known at different asphalt contents. To investigate rutting susceptibility for different mixes under study, a dynamic uniaxial loading in which the dynamic stress intensities were varied within a certain range to simulate field conditions was conducted. All mixtures studied in fatigue showed that the crack propagation rate versus stress intensity factors can be represented with a polynomial of a second degree. Statistical relations were developed to correlate the rutting and fatigue parameters under investigation in this study with other mix variables. The rutting parameters were found mostly to be influenced by asphalt contents and aggregate type. The fatigue parameters were found to be affected by asphalt contents, gradations and modulus of elasticity.

Elmitiny, M. R. N.

1980-03-01

78

Extending Flexible Pavement Life  

Microsoft Academic Search

Geogrid technology has developed steadily since the products were first introduced in the early 1980's. The initial geogrid products rapidly gained popularity within the civil engineering industry, principally due to their ability to provide simple, cost-effective solutions in various roadway and grade separation applications. They have gained widespread acceptance over the last 25 years as a solution to problems associated

Jim Penman; Joe Cavanaugh

79

Guidance for M-E Pavement Design Implementation.  

National Technical Information Service (NTIS)

The Mechanistic-Empirical Pavement Design guide developed under the National Cooperative Highway Research Program represents a dramatic change in how both rigid and flexible pavements are analyzed and designed. Recognizing the limitations of the current d...

D. H. Timm K. P. Davis R. E. Turochy

2010-01-01

80

Prefabricated Vertical Drains and Pavement Drainage Systems,  

National Technical Information Service (NTIS)

The 7 papers in the report deal with the following areas: Design, construction, and evaluation of West Virginia's first free-draining pavement system; Subbase permeability and pavement performance; Core flow-capacity requirements of geocomposite fin-drain...

J. S. Baldwin D. C. Long K. L. Highlands G. L. Hoffman B. J. Dempsey

1988-01-01

81

Implication of Aggregates in the Construction and Performance of Sea Coat Pavement Overlays (Revised).  

National Technical Information Service (NTIS)

The overall objective of this study, of which this research is the first phase, is to investigate and develop design criteria which will provide and maintain adequate pavement friction. Specifically, these objectives are to: develop a comprehensive, long-...

A. H. Meyer D. W. Fowler M. A. U. Abdul-Malak

1992-01-01

82

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...

83

Pavement Drainage and Pavement-Shoulder Joint Evaluation and Rehabilitation  

Microsoft Academic Search

The objectives of this research were i) to evaluate the performance of pavement subdrainage systems ii) study the behavior of moisture conditions below pavements and iii) provide recommendations for unproved drainage criteria based on analysis of field data. Existing and retrofitted subdrainage collector systems were inspected through external visual inspection in combination with a probe for internal inspection. Distresses and

Zubair Ahmed; Thomas D. White; Philippe L. Bourdeau

1993-01-01

84

High altitude premium pavements  

NASA Astrophysics Data System (ADS)

The effect on performance that various additives and, or compaction had on the performance of pavements was evaluated. The following additives were evaluated: Anti-stripping additives, ground scrap rubber and carbon black. Samples were also evaluated at approximately 0, 3, 10 and 15% voids to determine the effect compaction had on the performance of the pavement. The resilient modulus, effect of water on cohesion of compacted bituminous mixtures and an accelerated moisture damage test was performed on each design mix. Most of the additives did not show significant, if any, improvement in the laboratory test results. The best improvement in laboratory test results came from the anti-stripping asphalt additives, which is one of the least costly and simplest to include in the pavement mixture.

Abel, F.; Proctor, J.

1980-02-01

85

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

86

Influence of binder and mixture properties on the performance of AC pavements  

Microsoft Academic Search

This study was conducted as a part of an on-going program to validate the SUPERPAVE binder selection program introduced in the U.S. in 1995. The SUPERPAVE system recognizes that the behavior of hot mix asphalt (HMA) depends on the temperature, loading and aging conditions and allow for material selection process that aids in the prevention of premature pavement distress. To

Ayesha Shah

2004-01-01

87

Construction, Testing and Performance Report on the Resin Modified Pavement Demonstration Project.  

National Technical Information Service (NTIS)

Resin Modified Pavement (RMP) is a composite paving material consisting of a thin layer (2 inches) of open graded hot mix asphalt (HMA) whose internal air voids (approximately 30% voids) are filled with a latex rubber-modified portland cement grout. The o...

J. S. Whittington R. L. Battey

2007-01-01

88

Experimental pavement delineation treatments  

NASA Astrophysics Data System (ADS)

Visibility and durability of materials used to delineate shoulders and medians adjacent to asphalt pavements were evaluated. Materials evaluated were polysulfide and coal tar epoxies, one and two component polyesters, portland cement, acrylic paints, modified-alkyd traffic paint, preformed plastic tape, and thermoplastic markings. Neat applications, sand mortars, and surface treatments were installed in several geometric patterns including cross hatches, solid median treatments, and various widths of edge lines. Thermoplastic pavement markings generally performed very well, providing good visibility under adverse viewing conditions for at least 4 years. Thermoplastic 4 in. wide edge lines appear to provide adequate visibility for most conditions.

Bryden, J. E.; Lorini, R. A.

1981-06-01

89

Determination of Coefficient of Thermal Expansion Effects on Louisiana's PCC Pavement Design.  

National Technical Information Service (NTIS)

With the development of the Mechanistic Empirical Pavement Design Guide (MEPDG) as a new pavement design tool, the coefficient of thermal expansion (CTE) is now considered a more important design parameter in estimating pavement performance including crac...

H. C. Shin Y. Chung

2011-01-01

90

Pavement Roughness and Rideability.  

National Technical Information Service (NTIS)

The report contains a description of a new method for assessing pavement roughness. The method is based on a statistical transform between the physical measure of a pavement profile and the subjective rating of pavement rideability. This transform is expr...

M. S. Janoff J. B. Nick P. S. Davit G. F. Hayhoe

1985-01-01

91

Permanent Deformation Potential in Asphalt Concrete Overlay Over Portland Cement Concrete Pavements.  

National Technical Information Service (NTIS)

Rutting potential in asphalt concrete pavements (ACP) over both flexible (granular), and rigid (PCC) pavements is investigated. A detailed analysis of the influence of ACP mixture stiffness, stiffness ratios between the ACP surface and the supporting base...

D. N. Little M. Ameri-Gaznon

1988-01-01

92

Development of Predictive Equations Based on Pavement Condition Index Data.  

National Technical Information Service (NTIS)

This research project evaluated runway pavement condition survey information in order to develop models or equations capable of predicting future pavement performance and projected life expectancy. The data was obtained from the Federal Aviation Administr...

C. V. Floro

1992-01-01

93

OVERVIEW OF AN ACCELERATED PAVEMENT TESTING STUDY TO ASSESS THE PERFORMANCE OF MODIFIED BINDERS IN ASPHALT CONCRETE OVERLAYS  

Microsoft Academic Search

A comprehensive laboratory and accelerated pavement testing study on the use of terminal blend modified binders to limit reflective cracking in thin asphalt concrete overlays has recently been completed at the University of California Pavement Research Center. The experiment entailed the construction of a 90 m test road consisting of compacted clay subgrade, a 410 mm aggregate base and 90

D Jones; J Harvey; T Bressette

94

LIFE CYCLE COST ANALYSIS OF PORTLAND CEMENT CONCRETE PAVEMENTS  

Microsoft Academic Search

Project conducted in cooperation with the Federal Highway Administration. 16. Abstract This report describes the development of a new life cycle cost analysis methodology for portland cement concrete pavements — one that considers all aspects of pavement design, construction, maintenance, and user impacts throughout the analysis period. It predicts pavement performance using state-of-the-art performance models and reliability concepts, from which

William James Wilde; Steve Waalkes; Rob Harrison

1999-01-01

95

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

SciTech Connect

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

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

1990-12-01

96

A design system for rigid pavement rehabilitation  

NASA Astrophysics Data System (ADS)

The development, use, and applicability of a rigid pavement rehabilitation design system, RPRDS, developed for use by the Texas State Department of Highways and Public Transportation is described. Like other pavement design systems, RPRDS makes use of the systems approach to incorporate a number of pavement design and analytical models into a computer program, RPRDS-1, for the generation, analysis, and comparison of numerous pavement design strategies. Basically, RPRDS generates a number of feasible overlay design strategies based on user inputs, performs a present value cost analysis on each, and then presents those which are optimal.

Seeds, S. B.; McCullough, B. F.; Hudson, W. R.

1982-01-01

97

A Design Model for Geosynthetic-reinforced Pavements  

Microsoft Academic Search

The first paper to this companion series of articles [Perkins, S.W and Edens, M.Q. (2003) “Finite elements and distress models for geosynthetic-reinforced pavements”, International Journal of Pavement Engineering, 3(4), 239–250] described a finite element response model and empirical damage models that were combined to form a mechanistic–empirical (M–E) for geosynthetic-reinforced flexible pavement systems. The model provides predictions of an extension

S. W. Perkins; M. Q. Edens

2003-01-01

98

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

99

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

100

Shear Fatigue Behaviour of Tack Coats in Pavements  

Microsoft Academic Search

For many years, pavement engineers use mechanistic design methods that are based on algorithms to compute stresses, strains and displacements in a flexible pavement structure, or in a multi-layered structure in general. Most of these methods assume, to ease the modelling of the structure and the computation process, that the layers are fully bonded or completely unbounded to each other.

Malick Diakhate; Annabelle Phelipot; Anne Millien; Christophe Petit

2006-01-01

101

Predicting pavement distress in oil field areas  

SciTech Connect

A study on oil field traffic characteristics was performed and a procedure was developed for assessing current and future effects of oil field truck traffic on surface-treated (stage construction type) pavements. A computer program calculates several types of pavement distress and serviceability parameters to evaluate pavement performance under various axle load repetitions. Stepwise regression analysis of 132 surface-treated pavement sections led to the development of individual distress equations for rutting, raveling, flushing, alligator cracking, patching, longitudinal and transverse cracking, and failures (potholes). The versatility of the program provides a means of anticipating early pavement failures due to increased axle load repetitions. The program also provides the basic framework for computing the effects of other ''special-use'' truck traffic demands.

Mason, J.M.; Scullion, T.; Stampley, B.E.

1983-05-01

102

Predicting pavement distress in oil field areas  

SciTech Connect

A study on oil field traffic characteristics was performed and a procedure was developed for assessing current and future effects of oil field truck traffic on surface-treated (stage construction type) pavements. A computer program calculates several types of pavement distress and serviceability parameters to evaluate pavement performance under various axle load repetitions. Stepwise regression analysis of 132 surface-treated pavement sections led to the development of individual distress equations for rutting, raveling, flushing, alligator cracking, patching, longitudinal and transverse cracking, and failures (potholes). The versatility of the program provides a means of anticipating early pavement failures due to increased axle load repetitions. The program also provides the basic framework for computing the effects of other ''special-use'' truck traffic demands.

Mason, J.M.; Scullion, T.; Stampley, B.E.

1984-05-01

103

Simulated aircraft load testing and non-destructive evaluation of bituminous pavements  

Microsoft Academic Search

The US Federal Aviation Administration's National Airport Pavement Test Facility was constructed to generate full-scale accelerated pavement test data for the development of advanced airport pavement design criteria. During the first round of traffic testing, a six-wheel (Boeing 777) landing gear and a four-wheel (Boeing 747) landing gear were trafficked on flexible test pavements until they were deemed failed. Non-destructive

Kasthurirangan Gopalakrishnan; Marshall R. Thompson

2008-01-01

104

Pavement Roughness and Serviceability.  

National Technical Information Service (NTIS)

The Pennsylvania Department of Transportation, through the Pavement Evaluation Section in the Bureau of Materials, Testing and Research, has been doing research since 1968 in the field of pavement roughness trends. The interim report concerns the program ...

J. G. Hopkins

1972-01-01

105

Pavement Management and Evaluation.  

National Technical Information Service (NTIS)

The 9 papers in this report deal with the following areas: optimization of long-range major rehabilitation of airfield pavements; development and implementation of Alberta's pavement information and needs system; predicting reductions in service life of s...

D. H. Artman J. S. Liebman M. I. Darter M. A. Karan T. J. Christison

1983-01-01

106

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

107

Prediction of pavement roughness  

NASA Astrophysics Data System (ADS)

A simplified procedure has been developed for considering roughness in pavement design. The procedure utilizes statistical parameters to generate stochastic pavement material properties and profiles. A methodology was developed for predicting the rutting of a pavement section due to applied traffic. Thus the predicted rut depth can be applied to the profiles yielding a predicted surface profile. This profile can then be used to determine a measure of pavement roughness.

Barker, W. R.

1982-09-01

108

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

109

Fracture of highway and airport pavements  

NASA Astrophysics Data System (ADS)

Existing solutions for the stresses in a cracked slab containing a crack and supported by an elastic foundation are extended to obtain the stress intensity factor (SIF) for a crack in a pavement subjected to moving vehicular loads. In the existing solutions the stresses can be obtained only for a uniform bending stress (before the crack occurs) along the crack surface. For pavements subjected to moving vehicular loads, the stress distribution along the crack surface is not uniform and the approximation of a uniform stress is often unsatisfactory. The present work extends the above solutions to cover more realistic loading of highway and airport pavements. This facilitates the application of the principles of fracture mechanics to the fatigue crack propagation and fracture of pavements. Beginning with a part-through semi-elliptical starter crack, the crack is assumed to grow under load and the SIF is presented at various stages of crack growth, from the starter crack into a short through-crack that eventually becomes a very long through-crack. Some examples of the fracture of typical rigid and flexible highway and airport pavements are presented to show the need to consider fracture in the design of pavements.

Ramsamooj, D. V.

1993-03-01

110

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

111

Effect of skewed joints on the performance of jointed concrete pavement through 3D dynamic finite element analysis  

Microsoft Academic Search

The effect of skewing the transverse joints in concrete rigid pavements is studied through 3D finite element modelling. Models of multi-layered systems consisting of Portland cement concrete slabs, base and subgrade were developed. These consisted of slabs having straight as well as skewed joints. In order to study the state of stresses and strains in both straight and skewed slabs,

Mourad Y. Riad; Samir N. Shoukry; Gergis W. William; Michel R. Fahmy

2009-01-01

112

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

113

Effective Tool for Enhancing Elastostatic Pavement Diagnosis  

Microsoft Academic Search

The falling weight deflectometer (FWD) test is one of the most com- monly used tools for nondestructive evaluation of flexible pavements. Although the test is intrinsically dynamic, the state-of-practice back- calculation techniques used to interpret the FWD records are primarily elastostatic based, partly because of the high computational cost of dynamic multilayered solutions. It has long been known that the

Bojan B. Guzina; Robert H. Osburn

2002-01-01

114

Performance of a wing with nonuniform flexibility in hovering flight  

NASA Astrophysics Data System (ADS)

The deformability of insect wings is associated with the embedded skeleton (venation). In this paper, the aerodynamic performance of wings with nonuniform flexibility is computationally investigated. By using a two-dimensional rendition, the underlying veins are modeled as springs, and the membrane is modeled as a flexible plate. The focus is on the effects of the detailed distribution of vein flexibility upon the performance of such a wing in the generation of lift force. Specifically, we are interested in finding the importance of leading edge strengthening. Towards this end, the aerodynamic performances of three wings, a rigid wing, a flexible wing with identical veins, and a flexible wing with strengthened leading edge, are studied and compared against each other. It is shown that the flexible wing with leading edge strengthening is capable of producing significantly higher lift force without consuming more energy. This is found to be related to the stabilizing and cambering effects at the leading edge, which enhances the leading edge vortices. In addition, in contrast to the other two wings, which show sensitivity to kinematic parameters, the wing with strengthened leading edge perform well over a wide range of parameters.

Shoele, Kourosh; Zhu, Qiang

2013-04-01

115

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...

116

Design of perpetual asphalt pavements  

Microsoft Academic Search

The design conception of overseas perpetual pavement is introduced. Based on the successful experience on the improvement of asphalt pavement structure abroad,which can change the prensent situation of using single semi-rigid base asphalt pavements in our country,the design method of perpetual asphalt pavement is studied.The different pavement structures can be applied reasonablely.The earlier impairments of asphalt pavements can be prevented

Chang Hongxing; Zhao Jun; Tang Jiyu

2011-01-01

117

Performance Evaluation of Hot and Cold Pour Crack Sealing Treatments on Asphalt Surfaced Pavements (Revised).  

National Technical Information Service (NTIS)

This study is a continuation of an ongoing process of monitoring performance of treatment procedures using two types of crack sealants. The main objective of the analysis in this report is to compare the long-term performance of hot pour sealants to that ...

Y. Yildirim A. Qatan T. W. Kennedy

2003-01-01

118

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

Microsoft Academic Search

The purpose of this research was to study and evaluate the role that asphalt cracking. As part of the Strategic Highway Research Program (SHRP) new specifications for asphalt binders were developed that are based on the performance of the material. The asphalt binder graded and specified according to these new performance-based specifications is called PG binder. These new specifications are

S. W. Loh; J. Olek

1999-01-01

119

Analytical performance models for closed-loop flexible assembly systems  

Microsoft Academic Search

Flexible Assembly Systems (FASs), which form an important subset of modern manufacturing systems, are finding increasing use in today's industry. In the planning and design phase of these systems, it is useful to have tools that predict system performance for various operating conditions. In this article, we present such a performance analysis tool based on queueing approximation for a class

Manjunath Kamath; Rajan Suri; Jerry L. Sanders

1988-01-01

120

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

121

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

122

Extending the Life of Asphalt Pavements (OR09-086A), Part I (1).  

National Technical Information Service (NTIS)

The goal of this project was to identify common features of good and poorly performing asphalt pavements. The types of asphalt pavements included in the study were grouped into four categories: new construction, crush & shape with HMA surface, mill & resu...

H. L. Von Quintus R. Perera

2011-01-01

123

Development of a Rigid Pavement Forensics Knowledge Management System to Retain TxDOT Corporate Knowledge.  

National Technical Information Service (NTIS)

This report summarizes cooperative efforts to gather and make available in a knowledge management system both tacit and currently documented knowledge of rigid pavement forensic methods, tools, and the valuable insights into rigid pavement performance pri...

P. E. Krugler C. M. Chang-Albitres R. L. Robideau

2006-01-01

124

Underwater performance of flexible microgripper and fine particle manipulation  

NASA Astrophysics Data System (ADS)

Underwater performance of the microfabricated flexible microgripper (FMG) using Lorentz force actuation and electrothermal bimorph actuation is presented here. The Lorentz force actuation was a primary factor of the actuation for the underwater operation of FMG. We have manipulated the polystyrene fine particles successfully by using the FMG in water.

Suzuki, Yoshihiko

1994-10-01

125

Practical applications of nondestructive evaluation for airport pavement analysis  

NASA Astrophysics Data System (ADS)

This paper discusses the equipment and methodologies currently used for nondestructive testing (NDT) and nondestructive evaluation (NDE) of the structural capacity of military and civil airport pavements, including: (1) commonly used equipment and test methods for measuring pavement response to dynamic loads; (2) qualitative and quantitative evaluation of NDT data; (3) methods for back-calculating layer properties from NDT data; (4) layered elastic methods for evaluating pavement performance using processed NDT data; and (5) application of analytical results for developing pavement rehabilitation and management strategies.

McQueen, Roy D.; Guo, Edward

1995-07-01

126

High-performance graphene-based transparent flexible heaters.  

PubMed

We demonstrate high-performance, flexible, transparent heaters based on large-scale graphene films synthesized by chemical vapor deposition on Cu foils. After multiple transfers and chemical doping processes, the graphene films show sheet resistance as low as ?43 Ohm/sq with ?89% optical transmittance, which are ideal as low-voltage transparent heaters. Time-dependent temperature profiles and heat distribution analyses show that the performance of graphene-based heaters is superior to that of conventional transparent heaters based on indium tin oxide. In addition, we confirmed that mechanical strain as high as ?4% did not substantially affect heater performance. Therefore, graphene-based, flexible, transparent heaters are expected to find uses in a broad range of applications, including automobile defogging/deicing systems and heatable smart windows. PMID:22082041

Kang, Junmo; Kim, Hyeongkeun; Kim, Keun Soo; Lee, Seoung-Ki; Bae, Sukang; Ahn, Jong-Hyun; Kim, Young-Jin; Choi, Jae-Boong; Hong, Byung Hee

2011-11-21

127

Evaluation of non-uniform tyre contact stresses on thin asphalt pavements  

Microsoft Academic Search

Improved quantification of the shape and distribution of actual tyre-pavement contact stresses resulted in enhanced definitions of 3D-tyre-pavement contact stresses for the design and analysis of flexible pavements. It is now possible to describe the 3D-load\\/stress regimes with a series of discrete load values that were measured using Stress-In-Motion (SIM) technology, as well as being predicted from trained Artificial Neural

M De Beer; C Fisher; F J Jooste

128

The Effect of a Fabric Membrane on the Structural Behaviour of a Granular Road Pavement.  

National Technical Information Service (NTIS)

The performance under vehicle loading of an unbound granular pavement laid on a soft clay subgrade was compared with that of a similar pavement which included a fabric membrane between the granular material and the soil. The pavements were trafficked simu...

J. F. Potter E. W. H. Currer

1981-01-01

129

SEASONAL AND LOAD RESPONSE INSTRUMENTATION OF THE WAY30 PERPETUAL PAVEMENTS  

Microsoft Academic Search

A perpetual asphalt concrete pavement test section was completed along US-30 in Wayne County, OH, as part of the Wooster by-pass, in the fall of 2005. This project represents a collaborative effort between the Ohio Department of Transportation (ODOT) and the asphalt concrete paving industry with the purpose of evaluating the performance of these novel pavements. Perpetual asphalt concrete pavements

Michael T. Romanello

130

Enhanced Performance in Flexible Binder-free SWCNT Membrane EDLC  

NASA Astrophysics Data System (ADS)

We present results on an aqueous symmetric double layer electrochemical capacitor (EDLC) constructed with flexible binder-free single wall carbon (SWCNTs) membrane as electrodes. The capacitors were cycled from 0 to 1V @ 10 A/g for 10,000 cycles with 99.9% coulombic efficiency and 94% energy efficiency, and 100% depth of discharge. The power performance of the aqueous symmetric SWCNTs membrane capacitor is almost 100 --1000 times better than commercial non-aqueous EDLC capacitors.

Ma, Danhao; Shetty, Pralav; Adu, Kofi; Rajagopalan, Ramakrishnan

2013-03-01

131

Pavement Management Activities.  

National Technical Information Service (NTIS)

The 12 papers in the report deal with the following areas: development and implementation of a new rehabilitation information and priority programming system (RIPPS); dynamic decision model for a pavement management system; life-cycle costing of paved Ala...

M. A. Karan R. C. G. Haas A. Cheetham T. J. Christison S. M. Khalil

1984-01-01

132

Pavement Distresses at Intersections.  

National Technical Information Service (NTIS)

Asphaltic concrete pavements at intersections and their approaches, where traffic is required to stop and start, exhibit several types of distress. Among the more prominent forms of these distresses are deep rutting, pushing and shoving, and severe washbo...

D. Q. Hunsucker B. W. Meade

1995-01-01

133

Mediaprocessors in medical imaging for high performance and flexibility  

NASA Astrophysics Data System (ADS)

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

Managuli, Ravi; Kim, Yongmin

2002-05-01

134

Resonance and propulsion performance of a heaving flexible wing  

NASA Astrophysics Data System (ADS)

The influence of the bending rigidity of a flexible heaving wing on its propulsive performance in a two-dimensional imposed parallel flow is investigated in the inviscid limit. Potential flow theory is used to describe the flow over the flapping wing. The vortical wake of the wing is accounted for by the shedding of point vortices with unsteady intensity from the wing's trailing edge. The trailing-edge flapping amplitude is shown to be maximal for a discrete set of values of the rigidity, at which a resonance occurs between the forcing frequency and a natural frequency of the system. A quantitative comparison of the position of these resonances with linear stability analysis results is presented. Such resonances induce maximum values of the mean developed thrust and power input. The flapping efficiency is also shown to be greatly enhanced by flexibility.

Michelin, Sébastien; Llewellyn Smith, Stefan G.

2009-07-01

135

Long Term Pavement Response Data System using In-Situ Instrumentation  

Microsoft Academic Search

The large majority of New Zealand's road network is constructed from thin surfaced unbound flexible pavements where a granular layer provides the main structural strength of the pavement. The current AUSTROADS1 empirical design theory states that permanent deformation is largely attributed to the subgrade and that shape loss in the granular layers is simply a consequence of a previously deformed

B J Hayward; Pavements Engineer

136

Effect of temperature variation on pavement responses using 3D multilayered elastic analysis  

Microsoft Academic Search

The response of flexible pavement is largely influenced by the resilient modulus of the pavement profile. Different methods\\/approaches have been adopted in order to estimate or measure the resilient modulus of each layer assuming an average modulus within the layer. To account for the variation in the modulus of elasticity with depth within a layer, the layer should be divided

Wael Alkasawneh; Ernian Pan; Feng Han; Ronghua Zhu; Roger Green

2007-01-01

137

Performance-based design and analysis of flexible composite propulsors  

NASA Astrophysics Data System (ADS)

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

Motley, Michael R.; Young, Yin L.

2011-11-01

138

Training Development for Pavement Preservation.  

National Technical Information Service (NTIS)

This research project strives to help the Iowa Department of Transportation (DOT) fully achieve the full benefits of pavement preservation through training on proper selection, design, and application of pavement preservation treatments. In some cases, th...

A. Morandeira C. T. Jahren J. Mallen

2013-01-01

139

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

140

Airfield Rigid Pavement Structural Design-A Review of Main Aspects and Methods of Analysis  

NASA Astrophysics Data System (ADS)

Airfield pavements present a number of characteristics that make their design considerably different from that of road pavements. Apart from load magnitude and it's frequency, maintenance issues and pavement strength classification reporting are aspects that must be considered in the design phase. In the present paper, these aspects are analysed in the light of traditional and new methods of airfield pavement analysis. Parametric studies are performed in order to study the effects of different factors, such as pavement structure, layer thickness, material strength, effects of temperature, load transfer across joints and traffic characteristics.

Tiago Bonucci, Pereira

2010-05-01

141

Development of Methodology to Include the Strength Contribution of Select Subgrade Materials in Pavement Structure.  

National Technical Information Service (NTIS)

This study was conducted to develop a methodology to incorporate the structural contribution of working platforms, including those constructed with industrial by-products, into the design of flexible pavements. Structural contribution of the working platf...

T. B. Edil C. H. Benson W. H. Kim B. F. Tanyu

2005-01-01

142

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

143

Semiconducor wires and ribbons for high performance flexible electronics.  

SciTech Connect

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

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

2008-01-01

144

Information System Flexibility and the Performance of Business Processes  

Microsoft Academic Search

While insufficient flexibility of an information system to support a business process precludes the use of the system in certain cases, excessive flexibility of an information system can limit the usability of the system (Silver 1991), in addition to presenting an unnecessary investment. Despite a wealth of research on flexibility and its impacts on organizations and business processes (esp. manufacturing),

Judith Gebauer; Franz Schober

2005-01-01

145

Calibration of Mechanistic-Empirical Models for Cracking and Rutting of New Pavements Using Heavy Vehicle Simulator Tests  

Microsoft Academic Search

The Heavy Vehicle Simulator (HVS) is ideally suited for initial calibration of Mechanistic-Empirical models for pavement design. The HVS may be seen as a large scale laboratory equipment, with detailed control of materials, loads and environment, and with the possibility of carrying the tests through to failure. In-situ pavements, used for long term observation of pavement performance, are normally designed

Per Ullidtz; John Harvey; Khalid Ghuzlan; Bor-Wen Tsai; Bruce Steven

146

Evaluation of Pavement Surface Properties and Vehicle Interaction.  

National Technical Information Service (NTIS)

The papers in the report relate to skid resistance, road roughness, braking, vehicle control, pavement performance and serviceability, design, and measurement systems for evaluating surface properties and vehicle interaction.

J. C. Burns R. J. Peters

1973-01-01

147

Recommendations for Minimizing Poor Qualtiy Coarse Aggregate in Asphalt Pavements.  

National Technical Information Service (NTIS)

The Texas Department of Transportation has experienced with inconsistent performance of the coarse aggregate fraction of hot mix asphalt pavements. This project was initiated to address problems associated with variations in hot mix coarse aggregate quali...

J. P. Harris A. Chowdhury

2004-01-01

148

Investigation of the Frictional Resistance of Seal Coat Pavement Surfaces.  

National Technical Information Service (NTIS)

Numerous factors, including aggregate characteristics, construction variables, traffic volume, and environment, are believed to be affecting the frictional performance of highway pavements. The objective of this phase of the study was to investigate the e...

M. A. U. Abdul-Malak C. G. Papaleontiou D. W. Fowler A. H. Meyer

1988-01-01

149

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...

150

Rehabilitation Techniques for Stripped Asphalt Pavements.  

National Technical Information Service (NTIS)

Asphalt stripping is a fairly common form of distress for pavements in Montana, particularly for pavements that were surfaced with an open-graded friction course. Currently, the technique for rehabilitating these pavements involves the costly removal of m...

D. R. Johnson R. B. Freeman

2002-01-01

151

An experimental investigation on the aerodynamic performances of flexible membrane wings in flapping flight  

Microsoft Academic Search

An experimental study was conducted to assess the aerodynamic benefits of flapping flight compared with fixed-wing soaring flight for the development of flapping-wing Micro-Air-Vehicles (MAVs). The time-averaged aerodynamic performances (i.e. mean lift and thrust\\/drag) of two flexible membrane wings with different skin flexibility (i.e., a flexible nylon wing and a very flexible latex wing) were compared with that of a

Hui Hu; Anand Gopa Kumar; Gregg Abate; Roberto Albertani

2010-01-01

152

Damage Analysis of Jointed Plain Concrete Pavements in Indiana, Part I: Finite Element Modeling and Damage Analysis, Part II: INDISLAB, A Software for Jointed Plain Concrete Pavement Design  

Microsoft Academic Search

Current design procedures for concrete pavements do not account for several factors that can influence their service life. In this work, these factors are investigated and the findings are integrated into a procedure for better predicting longterm performance of concrete pavements. To achieve this, sophisticated finite element techniques are employed and parametric studies are performed. The findings are then integrated

Elisa D. Sotelino; Alireza Asgari; Andrew C. Saksa; Guillermo Cedeno

2005-01-01

153

MTG Flexible Combined Imager optical design and performances  

NASA Astrophysics Data System (ADS)

Meteosat Third Generation is the next ESA Program of Earth Observation dedicated to Nowcasting and very short term Weather Forecasting (NWC), medium/short range Global and Regional Numerical Weather Prediction (NWP), and Climate and Air Composition Monitoring. The satellites will be operating from the Geostationary orbit using a 3 axes stabilized platform. The main instrument is called the Flexible Combined Imager (FCI), currently under development by Thales Alenia Space France (TAS-F). This instrument will provide full images of the Earth every 10 minutes in 16 spectral channels between 0.44 and 13.3 ?m, with a ground resolution from 0.5 km to 2 km. The FCI is composed of a TMA telescope developed by Kayser-Threde (KT), which includes a Scan mirror, and a calibration mechanism with an embedded black body dedicated to accurate in-flight IR radiometric calibration and a Metallic Neutral density for dedicated VNIR Sun calibration. The image produced by the telescope is split into several spectral groups by a spectral separation assembly (SSA) with dichroïc beamsplitters. The output beams are collimated to ease the instrument integration, and reach the cold optics (CO-I) which focalize the optical beams onto the detectors. The cold optics and IR detectors are accurately positioned inside a common cryostat to improve registration between spectral channels. Spectral filters are integrated on top of the detectors in order to achieve the required spectral selection. This article will describe the optical design and the main optical performances of the FCI: image quality, very high line-of-sight stability, and an efficient stray-light rejection thanks to the implementation of dedicated baffles and a stringent control of contamination. The FCI currently under development is expected to exhibit a significant improvement of performances with respect to Meteosat Second Generation satellites.

Ouaknine, J.; Gode, S.; Napierala, B.; Viard, T.; Foerster, U.; Fray, S.; Peacoke, Patrick; Hartl, M.; Hallibert, P.; Durand, Y.

2013-09-01

154

Assessment and upgrading of in-service heavy duty pavements to long life  

Microsoft Academic Search

The context of long-life pavements (LLP) is winning specific international interest the last years; especially in regards to the upgrading of existing pavements to LLP, which constitutes the main focus of the present research study. For this reason, a detailed assessment of the in situ condition of a heavy-duty highway pavement was performed, based on a comprehensive long-term monitoring approach

Andreas Loizos

2006-01-01

155

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

SciTech Connect

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

Raad, L.; Saboundjian, S.

1997-05-01

156

Energy and temperature performance analysis of geothermal (ground source) heat pumps integrated with permeable pavement systems for urban run-off reuse  

Microsoft Academic Search

Geothermal (ground source) heat pumps (GHP) and permeable pavement systems (PPS) have demonstrated their effectiveness in both industry and academic research during recent decades. To meet the rising demand for sustainable, recyclable and energy efficient techniques, research has focused on the combination of techniques to enhance existing or develop new applications.This paper reports on an experimental programme that combined GHP

K. Tota-Maharaj; P. Grabowiecki; M. Scholz

2009-01-01

157

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...

158

Interaction of Vehicles and Pavements.  

National Technical Information Service (NTIS)

The 9 papers in this report deal with the following areas: problems encountered in using vehicle ride as a criterion of pavement roughness; evaluation of panel rating methods for assessing pavement ride quality; high-speed road monitoring system; use of r...

B. E. Quinn J. B. Nick M. S. Janoff P. G. Jordan J. Porter

1983-01-01

159

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

160

Performance characterization of flexible dipole rectennas for smart actuator use  

Microsoft Academic Search

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

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

2006-01-01

161

Sustainable Construction Case History: Fly Ash Stabilization of Recycled Asphalt Pavement Material  

Microsoft Academic Search

A case history is described where Class C fly ash was used to stabilize recycled pavement material (RPM) during construction\\u000a of a flexible pavement in Waseca, MN, USA. The project consisted of pulverizing the existing hot-mix asphalt (HMA), base,\\u000a and subgrade to a depth of 300 mm to form RPM, blending the RPM with fly ash (10% by dry weight) and

Lin Li; Craig H. Benson; Tuncer B. Edil; Bulent Hatipoglu

2008-01-01

162

Field performance of maintenance treatments constructed with reclaimed asphalt pavement (RAP). Final research report, September 1992-August 1994  

SciTech Connect

In the study, RAP was blended with recycling emulsions and conventional maintenance mixtures in attempts to improve its field performance as a maintenance mixture. RAP was also mixed with stabilizers and used as a base material in maintenance projects. Several field experiments were constructed throughout the state, and the report documents their performance.

Estakhri, C.K.

1994-11-01

163

Sensitivity of the LCA allocation procedure for BFS recycled into pavement structures  

Microsoft Academic Search

The purpose of this paper is twofold: to investigate the problems involved when performing an environmental assessment of various pavements structures and to establish the method applied to solutions proposed by official French guidelines. This assessment will be performed by employing the life cycle assessment (LCA) methodology specifically adapted to road pavements through a parametric environmental evaluation tool developed by

Shahinaz Sayagh; Anne Ventura; Tung Hoang; Denis François; Agnès Jullien

2010-01-01

164

Aggregate Toughness/Abrasion Resistance and Durability/Soundness Tests Related to Asphalt Concrete Performance in Pavements.  

National Technical Information Service (NTIS)

Numerous tests have been developed to empirically characterize aggregate without, necessarily, a strong relationship with the performance of the final products incorporating these aggregates. This seems to be particularly true for aggregate toughness and ...

Y. Wu F. Parker K. Kandhal

1998-01-01

165

Evaluation of Engineering Properties of Hot Mix Asphalt Concrete for the Mechanistic-Empirical Pavement Design  

Microsoft Academic Search

Hot Mix Asphalt (HMA) is a viscoelastic material and has been broadly used in pavement structures. It is important to understand the mechanism of complex behaviors of HMA mixtures in field for improving pavement mechanical performance. Aggregate gradation and asphalt binder are two key factors that influence the engineering properties of HMA. The asphalt binder plays a significant role in

Yuan Xiao

2009-01-01

166

Theoretical approach to electromagnetic monitoring of road pavement applied geophysics and stochastical model  

Microsoft Academic Search

Road pavement performances are of great importance for driving comfort and safety. Monitoring and rehabilitation activities are always extremely strategic and crucial. The points of strength of advanced non-destructive techniques for road pavement monitoring essentially are: (1) reliability, (2) significance in the space domain, (3) efficiency and (4) quickness. One of the most relevant and widely used technologies is the

Andrea Benedetto

2004-01-01

167

Validation of a Pavement Response Model Using Full-scale Field Tests  

Microsoft Academic Search

This paper provides details on a field verification program undertaken to validate the applicability of a finite-layer mechanistic model that has been selected to perform pavement response calculations. The proposed pavement response model is more realistic since it can handle moving traffic loading conditions, and it takes into consideration important factors such as vehicle speed and the non-uniform stress distributions

Raj V. Siddharthan; N. Krishnamenon; Mohey El-Mously; Peter E. Sebaaly

2002-01-01

168

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

169

Airport pavement NDE research at CQEFP  

NASA Astrophysics Data System (ADS)

The Center for Quality Engineering and Failure Prevention (CQEFP) at Northwestern University is actively involved in the development of new stress-wave based non-destructive evaluation techniques for airport pavements. This paper summarizes recent accomplishments and outlines current research directions. The development of a new stress-wave source is detailed first. The stress-wave generating technique allows for a high degree of control of the input stress wave while at the same time enabling the generation of significant wave amplitudes. Experimental results on concrete specimens demonstrate the controllability and penetrating ability of the developed stress wave generation technique. Its performance is compared to that of an impact source. Experimental results from an existing stress-wave based NDE technique, the impact-echo method, are presented and limitations of that approach are demonstrated. Finally, directions of future airport pavement NDE research at CQEFP, which focus upon application of the developed stress wave generation technique to pavement NDE problems, are outlined.

Popovics, John S.; Achenbach, Jan D.

1996-11-01

170

The use of flexible arm muscle synergies to perform an isometric stabilization task  

Microsoft Academic Search

ObjectiveTo evaluate if functional synergies are comprised of flexible combinations of a small number of ensembles of upper limb muscles to stabilize a particular performance variable during a force production task.

Vijaya Krishnamoorthy; John P. Scholz; Mark L. Latash

2007-01-01

171

Operating the Portable Seismic Pavement Analyzer.  

National Technical Information Service (NTIS)

The portable seismic pavement analyzer (PSPA) is a non-destructive testing device that measures the seismic modulus of concrete pavements. This report provides guidance on how to operate the PSPA including (a) general use and recommendations of the PSPA, ...

H. P. Bell

2006-01-01

172

A high speed profiler based slab curvature index for jointed concrete pavement curling and warping analysis  

NASA Astrophysics Data System (ADS)

One of the biggest gaps of missing knowledge between accurate structural modeling of concrete pavement slab behavior and real pavement behavior is accounting for slab warping (locked-in curvature and moisture gradient effects) and curling (temperature gradient effects). Curling and warping are curvatures that can be present in a PCC slab that can cause corners and edges, or mid panel, of the slab to lift off of the ground resulting in relatively high deflection and stress in the system. The least understood type of curvature in slabs is apparent locked-in curvature, which can become excessive and control the overall behavior of the pavement system. This project is focused on quantifying slab curvatures and the effects of apparent locked-in curvature on the behavior and long-term performance of pavement systems. A high-speed profile analysis technique for detecting the amount of slab curvatures along pavement wheel paths is described. This signal processing technique can detect relatively small curvature variations in high-speed pavement elevation profiles obtained at normal highway operating speeds using special vehicles. A resulting curvature detection algorithm is applied to the Federal Highway Administration (FHWA) Long Term Pavement Performance (LTPP) database high-speed pavement profiles for jointed concrete pavements. The range and nature of slab curvatures detected in the profiles is described. The calculated locked-in curvature at the various pavement sites is compared to LTPP database information to evaluate curvature effects on pavement deterioration rates and the relation between site parameters and locked-in curvature. The significance of slab curvature is shown through statistics and predictive models developed for various pavement distress modes. It is shown that the amount of curvature locked into concrete slabs is one of the strongest factors in the FHWA LTPP data correlated to deterioration of pavements. This study shows that preventing locked-in slab curvature should be a top priority for PCC slabs in highway applications. The profile analysis routine and distress prediction models developed will be valuable tools for pavement designers, managers, and researchers.

Byrum, Christopher Ronald

173

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

174

Strategic flexibility as a moderator of the relationship between commitment to employees and performance in service firms  

Microsoft Academic Search

This paper examines the fit between organizational commitment to employees (OCE) and strategic flexibility. The complementariness between these two factors originates from the fact that the effect of OCE on a firm's performance depends on the type of strategic flexibility. We argue that the greater the degree of strategic flexibility, the greater the positive effect of OCE on organizational performance.

Vicente Roca-Puig; Inmaculada Beltrán-Martín; Ana B. Escrig-Tena; Juan C. Bou-Llusar

2005-01-01

175

MODELING ISSUES FOR REAL-TIME PERFORMANCE IN FLEXIBLE MULTIBODY SYSTEMS  

Microsoft Academic Search

c.es Abstract. In recent years, our group has worked on real-time methods for the dynamics of flexible and rigid multi-body systems. In order to develop such methods, attention must be paid, in an integrated way, to modeling issues, formulation of the equations of motion, nu- merical integration procedures, and implementation techniques. Achievement of real-time performance in flexible multi-body systems on

Ruth Gutierrez; Urbano Lugris; Manuel Gonzalez; Javier Cuadrado

2005-01-01

176

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

Microsoft Academic Search

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

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

2011-01-01

177

High performance of a solid-state flexible asymmetric supercapacitor based on graphene films  

NASA Astrophysics Data System (ADS)

Solid-state flexible energy storage devices hold the key to realizing portable and flexible electronic devices. Achieving fully flexible energy storage devices requires that all of the essential components (i.e., electrodes, separator, and electrolyte) with specific electrochemical and interfacial properties are integrated into a single solid-state and mechanically flexible unit. In this study, we describe the fabrication of solid-state flexible asymmetric supercapacitors based on an ionic liquid functionalized-chemically modified graphene (IL-CMG) film (as the negative electrode) and a hydrous RuO2-IL-CMG composite film (as the positive electrode), separated with polyvinyl alcohol-H2SO4 electrolyte. The highly ordered macroscopic layer structures of these films arising through direct flow self-assembly make them simultaneously excellent electrical conductors and mechanical supports, allowing them to serve as flexible electrodes and current collectors in supercapacitor devices. Our asymmetric supercapacitors have been optimized with a maximum cell voltage up to 1.8 V and deliver a high energy density (19.7 W h kg-1) and power density (6.8 kW g-1), higher than those of symmetric supercapacitors based on IL-CMG films. They can operate even under an extremely high rate of 10 A g-1 with 79.4% retention of specific capacitance. Their superior flexibility and cycling stability are evident in their good performance stability over 2000 cycles under harsh mechanical conditions including twisted and bent states. These solid-state flexible asymmetric supercapacitors with their simple cell configuration could offer new design and fabrication opportunities for flexible energy storage devices that can combine high energy and power densities, high rate capability, and long-term cycling stability.Solid-state flexible energy storage devices hold the key to realizing portable and flexible electronic devices. Achieving fully flexible energy storage devices requires that all of the essential components (i.e., electrodes, separator, and electrolyte) with specific electrochemical and interfacial properties are integrated into a single solid-state and mechanically flexible unit. In this study, we describe the fabrication of solid-state flexible asymmetric supercapacitors based on an ionic liquid functionalized-chemically modified graphene (IL-CMG) film (as the negative electrode) and a hydrous RuO2-IL-CMG composite film (as the positive electrode), separated with polyvinyl alcohol-H2SO4 electrolyte. The highly ordered macroscopic layer structures of these films arising through direct flow self-assembly make them simultaneously excellent electrical conductors and mechanical supports, allowing them to serve as flexible electrodes and current collectors in supercapacitor devices. Our asymmetric supercapacitors have been optimized with a maximum cell voltage up to 1.8 V and deliver a high energy density (19.7 W h kg-1) and power density (6.8 kW g-1), higher than those of symmetric supercapacitors based on IL-CMG films. They can operate even under an extremely high rate of 10 A g-1 with 79.4% retention of specific capacitance. Their superior flexibility and cycling stability are evident in their good performance stability over 2000 cycles under harsh mechanical conditions including twisted and bent states. These solid-state flexible asymmetric supercapacitors with their simple cell configuration could offer new design and fabrication opportunities for flexible energy storage devices that can combine high energy and power densities, high rate capability, and long-term cycling stability. Electronic supplementary information (ESI) available: Photograph and AFM images, XPS spectra, XRD patterns, TGA curves, and evaluated values of energy and power densities are shown in the ESI. See DOI: 10.1039/c2nr30991b

Choi, Bong Gill; Chang, Sung-Jin; Kang, Hyun-Wook; Park, Chan Pil; Kim, Hae Jin; Hong, Won Hi; Lee, Sanggap; Huh, Yun Suk

2012-07-01

178

High performance of a solid-state flexible asymmetric supercapacitor based on graphene films.  

PubMed

Solid-state flexible energy storage devices hold the key to realizing portable and flexible electronic devices. Achieving fully flexible energy storage devices requires that all of the essential components (i.e., electrodes, separator, and electrolyte) with specific electrochemical and interfacial properties are integrated into a single solid-state and mechanically flexible unit. In this study, we describe the fabrication of solid-state flexible asymmetric supercapacitors based on an ionic liquid functionalized-chemically modified graphene (IL-CMG) film (as the negative electrode) and a hydrous RuO(2)-IL-CMG composite film (as the positive electrode), separated with polyvinyl alcohol-H(2)SO(4) electrolyte. The highly ordered macroscopic layer structures of these films arising through direct flow self-assembly make them simultaneously excellent electrical conductors and mechanical supports, allowing them to serve as flexible electrodes and current collectors in supercapacitor devices. Our asymmetric supercapacitors have been optimized with a maximum cell voltage up to 1.8 V and deliver a high energy density (19.7 W h kg(-1)) and power density (6.8 kW g(-1)), higher than those of symmetric supercapacitors based on IL-CMG films. They can operate even under an extremely high rate of 10 A g(-1) with 79.4% retention of specific capacitance. Their superior flexibility and cycling stability are evident in their good performance stability over 2000 cycles under harsh mechanical conditions including twisted and bent states. These solid-state flexible asymmetric supercapacitors with their simple cell configuration could offer new design and fabrication opportunities for flexible energy storage devices that can combine high energy and power densities, high rate capability, and long-term cycling stability. PMID:22751863

Choi, Bong Gill; Chang, Sung-Jin; Kang, Hyun-Wook; Park, Chan Pil; Kim, Hae Jin; Hong, Won Hi; Lee, SangGap; Huh, Yun Suk

2012-06-29

179

High Performance Fibers Based on Rigid and Flexible Polymers  

Microsoft Academic Search

This chapter covers recent developments in the production of well established high performance fibers such as Kevlar, PBO, Spectra and Dyneema fibers and depicts a new super strong M5. The latter fibers have the modulus of 330GPa and tenacity of 5GPa. DuPont de Nemours is currently developing commercial M5 fibers and yarns. A very interesting monomer namely, 2,5?dihydroxyterephthalic is used

Mehdi Afshari; Doetze J. Sikkema; Katelyn Lee; Mary Bogle

2008-01-01

180

On the improvement of tracking performance of flexible robot arm using FFT method  

Microsoft Academic Search

The problem of how to improve the transient performance of a single-link flexible robot arm rotating in a horizontal plane using FFT method is addressed in this paper. Lyapunov's direct method is used to prove the stability of the closed-loop system under the proposed control law. However, the performance of the system is limited by factors such as nonlinearity, lower

Lilong Cai; Xiaoqi Tang

1997-01-01

181

Evaluation of concrete pavement service life using 3D nonlinear finite element analysis and nonlinear fatigue damage model  

Microsoft Academic Search

Current design procedures for concrete pavements do not account for several factors that can influence their service life. In this work, these factors are investigated and the findings are integrated into a procedure for better predicting long-term performance of concrete pavements. To achieve this, sophisticated finite element techniques are employed and parametric studies are performed. The findings are then integrated

Alireza Asgari

2004-01-01

182

SOURCE CONTROL FOR WATERSHED PROTECTION: PERMEABLE PAVEMENT TECHNOLOGY  

Microsoft Academic Search

Permeable pavement systems remain largely unutilised in the Auckland, New Zealand region as outstanding questions regarding performance benefit versus long term cost and maintenance obligations have yet to be answered under local conditions. In response, a comprehensive field monitoring study is currently being conducted by the University of Auckland in conjunction with the North Shore City Council, the Auckland Regional

Elizabeth A. Fassman; Sam Blackbourn

2007-01-01

183

Overview of the 'PAVER' Pavement Management System and Economic Analysis of Field Implementing the 'PAVER' Pavement Management System.  

National Technical Information Service (NTIS)

This paper presents the results of an economic analysis performed on implementing the PAVER system at a military installation. PAVER is a pavement management system developed by the U.S. Army Corps of Engineers over the past 10 years for use by military i...

M. Y. Shahin S. D. Kohn

1982-01-01

184

Investigation of Recycling Bituminous Pavements.  

National Technical Information Service (NTIS)

Interest in cold-mixed in-place recycling of asphalt pavements is becoming more widespread. This final report summarized the findings of four major studies conducted over a period of 5 years. Guidelines were developed that would enable the paving engineer...

M. Tia A. Iida J. McKinney L. Wood

1983-01-01

185

Prevention of Early Pavement Deterioration.  

National Technical Information Service (NTIS)

This study was done to identify the major forms and causes of early pavement distress, and to recommend changes in specifications or policies to prevent the distress. Three major forms of distress in Utah were identified as follows: (1) Unstable mixes, (2...

D. I. Anderson D. E. Peterson M. L. Wiley

1978-01-01

186

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

187

Manual for Emulsion-Based Chip Seals for Pavement Preservation. National Cooperative Highway Research Program.  

National Technical Information Service (NTIS)

This report presents a manual for the use of emulsion-based chip seals for pavement preservation. The manual addresses the factors affecting chip performance, discusses design and construction considerations, and identifies procedures for selecting the ap...

A. Epps-Martin A. Lord D. Hoyt S. Shuler

2011-01-01

188

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...

189

Economic Analysis of Roadway Occupancy for Freeway Pavement Maintenance and Rehabilitation. Volume 2. Users Manual.  

National Technical Information Service (NTIS)

A computer program was developed to perform an Economic Analysis of Roadway Occupancy for Maintenance and Rehabilitation EAROMAR. The user specifies the pavement design and traffic. The program generates hourly traffic volume by trip purpose, direction an...

B. C. Butler

1974-01-01

190

Economic Analysis of Roadway Occupancy for Freeway Pavement Maintenance and Rehabilitation. Volume 3. Program Documentation.  

National Technical Information Service (NTIS)

A computer program developed to perform an Economic Analysis of Roadway Occupancy for Maintenance and Rehabilitation EAROMAR is documented. Input includes pavement design, thickness, lanes, project length, initial and final year traffic. The program gener...

B. C. Butler S. W. Hopkins

1974-01-01

191

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

Code of Federal Regulations, 2013 CFR

...survey that includes ride, distress, rutting, and surface friction (as appropriate); (iv) Traffic information including...analysis that includes ride, distress, rutting, and surface friction (as appropriate); (ii) A pavement performance...

2013-04-01

192

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

Code of Federal Regulations, 2013 CFR

...survey that includes ride, distress, rutting, and surface friction (as appropriate); (iv) Traffic information including...analysis that includes ride, distress, rutting, and surface friction (as appropriate); (ii) A pavement performance...

2013-04-01

193

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

Code of Federal Regulations, 2013 CFR

...survey that includes ride, distress, rutting, and surface friction (as appropriate); (iv) Traffic information including...analysis that includes ride, distress, rutting, and surface friction (as appropriate); (ii) A pavement performance...

2013-04-01

194

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

195

External and internal labour flexibility in Spain: a substitute or complementary effect on firm performance?  

Microsoft Academic Search

The contingent perspective in strategic human resource management maintains that it is necessary to observe the interaction between human resource practices by encouraging external and internal labour flexibility. An issue still to be resolved is whether this fit leads to a complementary or substitute effect on firm performance. In order to contribute to this debate, we examine how the relationship

Vicente Roca-Puig; Inmaculada Beltrán-Martín; Juan C. Bou-Llusar; Ana B. Escrig-Tena

2008-01-01

196

Effect of a Self-Locking Drive Mechanism on the Performance of a Flexible Robot Arm  

Microsoft Academic Search

In addressing the control problem of flexible robot arms, the dynamics of drive mechanisms are often neglected. This leads to inaccurate prediction of the actual behavior of the robotic manipulator through digital simulations, and to a deterioration in the performance of the controller when applied to the physical system. The focus of this study is to demonstrate the effects induced

Nabil G. Chalhoub; A. Galip Ulsoy

1990-01-01

197

The tribology of flexible magnetic recording media—the influence of wear on signal performance  

Microsoft Academic Search

The tribology of magnetic recording systems is different to conventional tribology in many important aspects and an understanding of this branch of the science is still in its infancy. This paper presents a review of one specific aspect of the tribology of flexible tape storage systems, that is wear of heads and media and the effect on signal performance. Based

J. L. Sullivan

1998-01-01

198

Location, Marketing, and the Financial Flexibility of Nonprofit Performing Arts Organizations in Second Tier Cities  

Microsoft Academic Search

This article examines the effect of location relative to other marketing factors on the financial flexibility of nonprofit performing arts organizations (PAOs). While product development and promotional and pricing strategies are important marketing factors, locational advantages have become an important strategic asset for the arts industry. Yet very little research has been done on the locational dimensions of this industry.

Christine A. Lai; Jessie P. H. Poon

2009-01-01

199

The Open Runtime Platform: A Flexible High-Performance Managed Runtime Environment  

Microsoft Academic Search

The Open Runtime Platform (ORP) is a high-performance managed runtime environment (MRTE) that features exact generational garbage collection, fast thread synchronization, and multiple coexisting just-in-time compilers (JITs). ORP was designed for flexibility in order to support experiments in dynamic compilation, garbage collection, synchronization, and other technologies. It can be built to run either Java ? or

Michal Cierniak; M arsha Eng; Neal Glew; James Stichnoth

2003-01-01

200

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.

201

Rigid Pavement Database: Overview and Data Collection Plan.  

National Technical Information Service (NTIS)

The rigid pavement (RP) database contains historical distress data obtained from more than 400 continuously reinforced concrete pavements (CRCP) and jointed concrete pavements (JCP) across the state of Texas. Data collection efforts began in 1974 and have...

T. Dossey T. Turen B. F. McCullough

1998-01-01

202

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

203

Pavement Evaluation Concepts Using Nondestructive Structural Evaluation and Pavement Condition Index.  

National Technical Information Service (NTIS)

A logical method for pavement evaluation utilizing both nondestructive procedures for structural analysis and pavement condition distress to identify maintenance needs is presented. Alternatives for maintaining desired serviceability are categorized as ro...

J. W. Hall

1987-01-01

204

Silicon nanomembranes for high-performance flexible photonic interconnects and devices  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate the practicality of using silicon nanomembranes for use in high performance flexible photonic interconnects and devices. Using two silicon nanomembrane transfer schemes, we demonstrate successful transfer of several photonic building blocks including large aspect ratio (>4000) and long (>5cm) strip waveguides, band engineered slow light (ng > 30) photonic crystal waveguides, 1xN (1x2 and 1x6) multimode interference couplers etc, on a flexible Kapton polyimide substrate. A two-step cleaving method is also developed and implemented to facilitate testing of the transferred flexible photonic components for the first time. Upon cleaving, the propagation loss in transferred ultralong strip waveguide (~5.7cm) is found to be 1.1dB/cm, which is comparable to that of waveguides on SOI.

Subbaraman, Harish; Xu, Xiaochuan; Rahimi, Nassibe; Hosseini, Amir; Chen, Ray T.

2012-02-01

205

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

206

Assessment of the Uretek Process on Continuously Reinforced Concrete Pavement, Jointed Concrete Pavement, and Bridge Approach Slabs.  

National Technical Information Service (NTIS)

This study evaluates the rehabilitation method utilizing the injection of Uretek (polyurethane) into the pavement structures on continuously reinforced concrete pavement (CRCP), jointed concrete pavement (JCP), and bridge approach slabs. The polyurethane ...

K. Gaspard M. Morvant

2004-01-01

207

Calibration of Pavement Response Models for the Mechanistic-Empirical Pavement Design Method.  

National Technical Information Service (NTIS)

Most pavement design methodologies assume that the tire-pavement contact stress is equal to the tire inflation pressure and uniformly distributed over a circular contact area. However, tire-pavement contact area is not in a circular shape and the contact ...

J. A. Prozzi R. Luo

2007-01-01

208

AUTOMATED PAVEMENT IMAGING PROGRAM (APIP) FOR PAVEMENT CRACKS CLASSIFICATION AND QUANTIFICATION - A PHOTOGRAMMETRIC APPROACH  

Microsoft Academic Search

The evaluation of pavement conditions is an important part of pavement management. Traditionally, pavement condition data are gathered by human inspectors who walk or drive along the road to assess the distresses and subsequently produce report sheets. This visual survey method is not only time consuming and costly but more importantly it compromises the safety of the field personnel. With

M. Mustaffar; T. C. Ling

1998-01-01

209

Fatigue life prediction of asphalt concrete pavement using a harmony search algorithm  

Microsoft Academic Search

This paper proposes an efficient Harmony Search (HS) algorithm for determining the material parameters of a fatigue cracking\\u000a model based on Accelerated Pavement Testing (APT). APT is preferred over typical laboratory experiments and testing because\\u000a APT can simulate field pavement performance. The main advantage of the HS heuristic algorithm is its ability to find the best\\u000a global solution of a

Youngchan Suh; Sungho Mun; Insoo Yeo

2010-01-01

210

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

2011-08-10

211

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

212

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

PubMed

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

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

2012-10-30

213

PLATT: A flexible platform for experimental research on team performance in complex environments  

Microsoft Academic Search

The present article introduces PLATT, a recently developed task environment for controlled experimental research on team performance\\u000a in complex environments. PLATT was developed to meet the research demands posed by the complexity that present-day teams face.\\u000a It consists of a flexible, modular software architecture and research-specific scenarios. The scenarios can target various\\u000a types of tasks (e.g., planning, problem solving, and

Wim Kamphuis; Peter J. M. D. Essens; Kees Houttuin; Anthony W. K. Gaillard

2010-01-01

214

The use of flexible arm muscle synergies to perform an isometric stabilization task  

PubMed Central

Objective To evaluate if functional synergies are comprised of flexible combinations of a small number of ensembles of upper limb muscles to stabilize a particular performance variable during a force production task. Methods Electromyographic (EMG) signals of wrist, elbow and shoulder muscles were recorded. Linear combinations of indices of the integrated EMG of nine muscles (muscle modes or M-modes) and their relationship to changes in the moment of force produced by the right arm of subjects about the horizontal axis of a handle were first determined. Uncontrolled manifold (UCM) analysis was performed to determine the extent to which variance of the M-modes acted to produce a consistent change in the moment of force. Results Subjects exhibited three M-modes, two of which were ‘reciprocal’ while the third mode was considered a co-contraction mode. The three M-modes were found to be combined to form synergies that produced a consistent change in the moment of force across repetitive trials. Variance in the M-mode space that led to consistent changes in the moment of force across repetitions was significantly higher than variance that tended to produce inconsistent changes in the moment of force. Conclusions Flexible combinations of activations of ensembles of muscles are organized to stabilize the value of or produce consistent changes in the value of important performance variables. Significance The study of flexible muscle synergies in healthy individuals paves the way to understanding abnormal postural and movement patterns in individuals with neurological disorders.

Krishnamoorthy, Vijaya; Scholz, John P; Latash, Mark L

2007-01-01

215

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

PubMed

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

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

2010-10-01

216

The sports performance application of vibration exercise for warm-up, flexibility and sprint speed.  

PubMed

Since the turn of the 21st century, there has been a resurgence of vibration technology to enhance sport science especially for power and force development. However, vibration exercise has been trialled in other areas that are central to athlete performance such as warm-up, flexibility and sprint speed. Therefore, the aim of this review was to attempt to gain a better understanding of how acute and short-term vibration exercise may impact on warm-up, flexibility and sprint speed. The importance of warming up for sporting performance has been well documented and vibration exercise has the capability to be included or used as a standalone warm-up modality to increase intramuscular temperature at a faster rate compared to other conventional warm-up modalities. However, vibration exercise does not provide any additional neurogenic benefits compared to conventional dynamic and passive warm-up interventions. Vibration exercise appears to be a safe modality that does not produce any adverse affects causing injury or harm and could be used during interval and substitution breaks, as it would incur a low metabolic cost and be time-efficient compared to conventional warm-up modalities. Acute or short-term vibration exercise can enhance flexibility and range of motion without having a detrimental effect on muscle power, however it is less clear which mechanisms may be responsible for this enhancement. It appears that vibration exercise is not capable of improving sprint speed performance; this could be due to the complex and dynamic nature of sprinting where the purported increase in muscle power from vibration exercise is probably lost on repeated actions of high force generation. Vibration exercise is a safe modality that produces no adverse side effects for injury or harm. It has the time-efficient capability of providing coaches, trainers, and exercise specialists with an alternative modality that can be implemented for warm-up and flexibility either in isolation or in conjunction with other conventional training methods. PMID:23679142

Cochrane, Darryl

2011-11-08

217

Pavement distress detection and severity analysis  

Microsoft Academic Search

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

E. Salari; G. Bao

2011-01-01

218

Pervious Pavement System Evaluation-Paper  

EPA Science Inventory

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

219

Microstructure-based identification of bitumen performance  

Microsoft Academic Search

Motivated by recent progress in both experimentation and the micromechanical description of the behavior of multi-composed materials, a multiscale model for asphalt is currently developed at the Christian Doppler laboratory for “Performance-Based Optimization of Flexible Pavements” at Vienna University of Technology. This model allows us to relate macroscopically observable asphalt properties to finer-scale information. Since the mechanical properties of asphalt

Klaus Stangl; Andreas Jäger; Roman Lackner

2006-01-01

220

Latex improvement of recycled asphalt pavement  

NASA Astrophysics Data System (ADS)

The performance of a single unmodified milled recycled asphalt concrete was compared to milled asphalt concrete modified by addition of three types of rubber latex. Latex was added at 2, 3, 5, and 8 percent latex by weight of asphalt in the asphalt concrete. Lattices used were a styrene butadiene (SBR), a natural rubber (NR), an acrylonitrile butadiene (NBR), and four varieties of out of specification SBR lattices. Marshall tests, while indecisive, showed a modest improvement in properties of SBR and NR added material at 3 and 5 percent latex. Addition of NBR latex caused deterioration in Marshall stability and flow over that of control. Repeated load tests were run using the indirect tensile test, analyzed by the VESYS program, which computes life of pavements. Repeated load tests showed improvement in asphalt concrete life when 3 and 5 percent SBR was added. Improvement was also shown by the out of specification SBR.

Drennon, C.

1982-08-01

221

Performance Enhancement with Low Stress and Anxiety Modulated by Cognitive Flexibility  

PubMed Central

Objective The purpose of this study was to compare cognitive flexibility abilities, stress, and anxiety between starters and non-starter athletes. Methods A total of 30 male professional-soccer and 40 professional-baseball athletes were recruited. Wisconsin Card Sorting Test (WCST) and Trail Making Test A & B (TMT A & B) were administered to assess cognitive flexibility during competition. The Korean version of the STAI form Y (STAI-KY) and Visual analogue scale for anxiety and stress were used to assess the anxiety and stress. Results The starter group had better cognitive function (fewer perseverative errors and rapid TMTB times) (Z=3.32, p<0.01; Z=2.20, p=0.03, respectively) and lower stress and anxiety (F=4.34, p=0.01; F=6.61, p<0.01, respectively) during competition than the non-starter group. Conclusion The better cognitive performances were negatively correlated with stress and anxiety. Current results suggested that cognitive flexibility would enhance human performance by modulation of the anxiety and stress during competition.

Park, Hyung Woo; Kee, Baik Seok; Na, Churl; Na, Do-Hyun E.; Zaichkowsky, Leonard

2011-01-01

222

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

223

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

PubMed

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

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

2013-07-05

224

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

225

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

NASA Astrophysics Data System (ADS)

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

Beg, Muhammad Arif

226

Accelerated Pavement Testing of Load Transfer through Aggregate Interlock and the influence of Crack Width and Aggregate Type - a case study  

Microsoft Academic Search

It is well known that performance of plain jointed concrete pavements depends on aggregate interlock to transfer load from the one slab to the next. In order to quantify the relative contribution of crack width and the strength of the aggregate to the long- term performance of a plain jointed pavement, experimental sections of road were built using different aggregates

P J Strauss; B D Perrie

227

Experimental AC (Asphalt Concrete) overlays of PCC pavement  

NASA Astrophysics Data System (ADS)

A series of experimental asphalt concrete (AC) overlays was constructed over an existing distressed portland cement concrete pavement on Interstate 80 near Boca, California. The experimental overlays included rubberized dense-graded AC, rubberized open-graded AC, a rubber flush coat interlayer, dense-graded AC with short polyester fibers and Bituthene interlayer strips. The report presents a description and discussion of AC mix batching, construction observations, laboratory testing, overlay covering, and initial performance evaluation.

Smith, R. D.

1983-11-01

228

Use of scrap rubber in asphalt pavement surfaces  

NASA Astrophysics Data System (ADS)

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 percent by weight were studied. Initial laboratory ice disbonding test results led to the development of a new paving material, Chunk Rubber Asphalt Concrete (CRAC), that uses larger pieces of rubber in a much denser asphalt concrete mix. Strength values doubled and ice disbonding performance was enhanced.

Eaton, Robert A.; Roberts, Richard J.; Blackburn, Robert R.

1991-12-01

229

Use of scrap rubber in asphalt pavement surfaces. Special report  

SciTech Connect

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 led to the development of a new paving material, Chunk Rubber Asphalt Concrete (CRAC), that uses larger pieces of rubber in a much denser asphalt concrete mix. Strength values doubled and ice disbonding performance was enhanced.

Eaton, R.A.; Roberts, R.J.; Blackburn, R.R.

1991-12-01

230

Road crack condition performance modeling using recurrent Markov chains and artificial neural networks  

Microsoft Academic Search

Timely identification of undesirable pavement crack conditions has been a major task in pavement management. Up to date, myriads of pavement performance models have been developed for forecasting pavement crack condition with the traditional preferred techniques being the use of regression relationships developed from laboratory and\\/or field statistical data. However, it becomes difficult for regression techniques to predict the crack

Jidong Yang

2004-01-01

231

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

232

Human Resource Flexibility as a Mediating Variable Between High Performance Work Systems and Performance  

Microsoft Academic Search

Much of the human resource management literature has demonstrated the impact of high performance work systems (HPWS) on organizational performance. A new generation of studies is emerging in this literature that recommends the inclusion of mediating variables between HPWS and organizational performance. The increasing rate of dynamism in competitive environments suggests that measures of employee adaptability should be included as

Inmaculada Beltrán-Martín; Vicente Roca-Puig; Ana Escrig-Tena; Juan Carlos Bou-Llusar

2008-01-01

233

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

234

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

235

Excogitated Composite Multifunctional Layer for Pavement Systems.  

National Technical Information Service (NTIS)

The study evaluated a three-dimensional excogitated composite multifunctional (ECM) layer design for pavement construction. Research was conducted in the design and selection of materials that would satisfy the geometry and multi-functional requirements o...

B. J. Dempsey

1995-01-01

236

Evaluation of Joint Sealants of Concrete Pavements.  

National Technical Information Service (NTIS)

This report document investigation of concrete pavement joint sealants which began with project 1371 'Evaluation of Joint Sealants.' The purpose of the continued investigation is to propose specification and test protocol for joint sealants in concrete pa...

A. H. Gurjar T. Tang D. G. Zollinger

1997-01-01

237

Avoiding Early Failure of Intersection Pavements.  

National Technical Information Service (NTIS)

The primary mode of failure of the intersections studied was rutting with shoving in some cases. The leading materials related cause of pavement failure was asphalt content in excess of the designed value. Most of the mixtures studied contained relatively...

M. Ameri-Gaznon J. W. Button D. Perdomo D. N. Little D. G. Zollinger

1989-01-01

238

Aircraft Tire/Pavement Pressure Distribution.  

National Technical Information Service (NTIS)

This report presents tire/pavement pressure distributions calculated for seven different aircraft tires. The tires are main gear equipment on a variety of Air Force aircraft. The calculations were made with a finite element tire model developed previously...

J. T. Tielking

1989-01-01

239

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

240

Automatic inspection of pavement cracking distress  

Microsoft Academic Search

This paper presents the image-processing algorithm customized for high-speed, real-time inspection of pavement cracking. In the algorithm, a pavement image is divided into grid cells of 8x8 pixels and each cell is classified as a non-crack or crack cell using the grayscale information of the border pixels. Whether a crack cell can be regarded as a basic element (or seed)

B. Xu; Y. Huang

2005-01-01

241

Wavelet-aided pavement distress image processing  

Microsoft Academic Search

A wavelet-based pavement distress detection and evaluation method is proposed. This method consists of two main parts, real-time processing for distress detection and offline processing for distress evaluation. The real-time processing part includes wavelet transform, distress detection and isolation, and image compression and noise reduction. When a pavement image is decomposed into different frequency subbands by wavelet transform, the distresses,

Jian Zhou; Peisen S. Huang; Fu-Pen Chiang

2003-01-01

242

Acute whole body vibration training increases vertical jump and flexibility performance in elite female field hockey players  

Microsoft Academic Search

Objective: To quantify the acute effect of whole body vibration (WBV) training on arm countermovement vertical jump (ACMVJ), grip strength, and flexibility performance.Methods: Eighteen female elite field hockey players each completed three interventions of WBV, control, and cycling in a balanced random manner. WBV was performed on a Galileo machine (26 Hz) with six different exercises being performed. For the

D J Cochrane; S R Stannard

2005-01-01

243

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

244

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

245

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

2013-09-25

246

Can We Build a Truly High Performance Computer Which is Flexible and Transparent?  

PubMed

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

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

2013-09-10

247

Can We Build a Truly High Performance Computer Which is Flexible and Transparent?  

PubMed Central

State-of-the art computers need high performance transistors, which consume ultra-low power resulting in longer battery lifetime. Billions of transistors are integrated neatly using matured silicon fabrication process to maintain the performance per cost advantage. In that context, low-cost mono-crystalline bulk silicon (100) based high performance transistors are considered as the heart of today's computers. One limitation is silicon's rigidity and brittleness. Here we show a generic batch process to convert high performance silicon electronics into flexible and semi-transparent one while retaining its performance, process compatibility, integration density and cost. We demonstrate high-k/metal gate stack based p-type metal oxide semiconductor field effect transistors on 4 inch silicon fabric released from bulk silicon (100) wafers with sub-threshold swing of 80?mV dec?1 and on/off ratio of near 104 within 10% device uniformity with a minimum bending radius of 5?mm and an average transmittance of ~7% in the visible spectrum.

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

2013-01-01

248

A numerical model for the computation of concrete pavement moduli: a non-destructive testing and assessment method  

Microsoft Academic Search

The falling weight deflectometer (FWD) non-destructive testing technique has been used to monitor and assess the behaviour and performance of rigid pavement systems. In addition to the full-scale site investigation, tests were also carried out with the aid of a specifically developed laboratory scaled model of the FWD.A rigorous finite element model was developed to analyse a multi-layered pavement system

J. N. Karadelis

2000-01-01

249

Evaluation of Geosynthetic Reinforced Flexible Pavement Systems Using Two Pavement Test Facilities.  

National Technical Information Service (NTIS)

The project was initiated to provide additional test section data to better define the influence of traffic loading type and geosynthetic reinforcement type. The loading provided to the test sections forming the basis of the models described above consist...

S. W. Perkins

2002-01-01

250

The role of flexibility in injury prevention and athletic performance: have we stretched the truth?  

PubMed

The use of stretching to prevent injury, off-set muscle soreness, and improve performance has been widely accepted and promoted in sports. However, little or no scientific evidence supports the practice, and recent research suggests that stretching, which increases flexibility beyond that needed for sport-specific movements, may cause injury. This article presents studies that have looked at the effects of stretching on injury and performance. Many earlier studies that showed benefits of stretching did not look at the effects of stretching alone; they also involved general cardiovascular workouts in the experimental but not control groups. More recent research shows that general fitness, rather than stretching, is a more important risk factor in injury prevention. This article also discusses studies of the relationship between joint laxity and injury and the role that stiffness may play in enhancing performance and preventing injury. Overall, the evidence suggests that increasing range of motion beyond function through stretching is not beneficial and can actually cause injury and decrease performance. These findings should be used to challenge common warm-up practices in athletics. PMID:15495679

Ingraham, Stacy J

2003-05-01

251

Alternate/Modified Binders for Asphalt Airfield Pavements.  

National Technical Information Service (NTIS)

This report documents a laboratory-based research effort to determine the effects of asphalt modifiers and alternate binders on asphalt airfield pavements. The modified binders were tested to determine their potential for reducing pavement deformation dis...

G. L. Anderton

1990-01-01

252

Sustainable Pavement Maintenance Practices. Research Results Digest 365.  

National Technical Information Service (NTIS)

This synthesis reports on the state of the practice in sustainable pavement maintenance and preservation. It is concerned and directed at quantifying and understanding how pavement maintenance and preservation practices minimize environmental impacts. The...

2011-01-01

253

An Investigation of the Smoothness Characteristics of Highway Pavement Surfaces.  

National Technical Information Service (NTIS)

The report briefly describes Illinois' study of riding quality of newly constructed pavement, modifications made to the sensing devices of the BPR-Type Roughometer to improve its capabilities in measuring short pavement sections and to increase the operat...

J. E. LaCroix

1976-01-01

254

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

255

Structural Evaluation Methodology for Pavements Based on Dynamic Deflections.  

National Technical Information Service (NTIS)

A framework for structural evaluation of pavements based on dynamic deflections is presented. A self-iterative procedure has been developed to estimate insitu Young's moduli of pavement layers by using the approach of inverse application of layered elasti...

W. Uddin A. H. Meyer W. R. Hudson K. H. Stokoe

1985-01-01

256

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

257

Evaluation of Pavement Damage due to New Tire Designs.  

National Technical Information Service (NTIS)

The objective of this study is to evaluate pavement damage due to new tire designs using accelerated pavement testing (APT) and finite element (FE) modeling. Three tire configurations were investigated in this study, including the newly developed wide-bas...

H. Wang I. L. Al-Qadi

2009-01-01

258

Molecular mechanisms controlling pavement cell shape in Arabidopsis leaves  

Microsoft Academic Search

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

Pingping Qian; Suiwen Hou; Guangqin Guo

2009-01-01

259

Surface Distresses Detection of Pavement Based on Digital Image Processing  

Microsoft Academic Search

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

Aiguo Ouyang; Chagen Luo; Chao Zhou

2010-01-01

260

AutoPAVER: A software package for automated pavement evaluation  

NASA Astrophysics Data System (ADS)

This research developed a method that improves data collection and reduces data entry times for Pavement Condition Index (PCI) surveys for use with PAVER, a pavement maintenance management system. The method, AutoPAVER, is a microcomputer software package used to analyze pictures of pavement surfaces and to forward the resulting analysis to PAVER. The user works interactively with the system to identify and classify pavement distresses. Distress measurement and data entry are done on the computer.

Ginsberg, Mark D.; Shahin, M. Y.; Walther, Jeanette A.

1990-07-01

261

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.

Krysi?ski, Lech; Sudyka, Jacek

2013-10-01

262

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

2010-11-10

263

Stabilized TiN nanowire arrays for high-performance and flexible supercapacitors.  

PubMed

Metal nitrides have received increasing attention as electrode materials for high-performance supercapacitors (SCs). However, most of them are suffered from poor cycling stability. Here we use TiN as an example to elucidate the mechanism causing the capacitance loss. X-ray photoelectron spectroscopy analyses revealed that the instability is due to the irreversible electrochemical oxidation of TiN during the charging/discharging process. Significantly, we demonstrate for the first time that TiN can be stabilized without sacrificing its electrochemical performance by using poly(vinyl alcohol) (PVA)/KOH gel as the electrolyte. The polymer electrolyte suppresses the oxidation reaction on electrode surface. Electrochemical studies showed that the TiN solid-state SCs exhibit extraordinary stability up to 15,000 cycles and achieved a high volumetric energy density of 0.05 mWh/cm(3). The capability of effectively stabilizing nitride materials could open up new opportunities in developing high-performance and flexible SCs. PMID:22947093

Lu, Xihong; Wang, Gongming; Zhai, Teng; Yu, Minghao; Xie, Shilei; Ling, Yichuan; Liang, Chaolun; Tong, Yexiang; Li, Yat

2012-09-07

264

INFLUENCE OF MODELLING AND NUMERICAL PARAMETERS ON THE PERFORMANCE OF A FLEXIBLE MBS FORMULATION  

Microsoft Academic Search

SYNOPSIS Recently, the authors have developed an efficient, robust, accurate and easy-to-implement method for the real-time analysis of rigid-flexible multibody systems. The flexible bodies are modelled by means of the floating frame of reference formulation, along with modal superposition of both static and dynamic modes. The dynamic modes to be considered for each flexible body must be decided by the

J. CUADRADO; R. GUTIERREZ

265

Dynamic Performance Analysis of a Certain Solid Rocket Motor Flexibility Nozzle  

Microsoft Academic Search

The decision of a particular model of solid rocket motor nozzle control precision and flexible functioning of the pivot center drift and systems for power moment problems, using computer-aided design and analysis methods, and establish flexible nozzle coupled rigid-flexible multi-body dynamic model; to role of the body in the system activity for work on the axial load resistance, for sine

Liu Wenzhi; Tian Weiliang; Wu Jianxin; Li Xiaoqin

2010-01-01

266

Evaluation of Temporary Pavement Marking Systems for Resurfacing Zones. Appendix B. Driver Comprehension of Temporary Pavement Marking Systems.  

National Technical Information Service (NTIS)

This document contains the results of the driver comprehension experiment of the selected temporary pavement marking systems, including the comprehension of selected traffic signs. The following temporary pavement marking systems were included in this stu...

H. T. Zwahlen T. Schnell

1996-01-01

267

Characterization of Unbound Pavement Materials From Virginia Sources for Use in the New Mechanistic-Empirical Pavement Design Procedure.  

National Technical Information Service (NTIS)

The implementation of mechanistic-empirical pavement design requires mechanistic characterization of pavement layer materials. The subgrade and base materials are used as unbound, and their characterization for Virginia sources was considered in this stud...

M. S. Hossain

2010-01-01

268

Full-Cost Approach to Airport Pavement Management  

Microsoft Academic Search

Airport pavements are a key element of the commercial airport infrastructure that often are taken for granted. The current Federal Aviation Administration (FAA) endorsed pavement management system developed in the 1970's does not meet the needs of U. S. commercial service airports because it ignores all modes of pavement failure other than surface distress. Not only is it a time

Robert Harrison

269

Development of laser system to measure pavement rutting  

Microsoft Academic Search

Asphalt pavement rutting is one of the most common and destructive pavement distresses observed on U.S. roads, particularly in the urban environment at intersections. They are an important indicator of the structural integrity of the pavement as well as having an impact on road user safety. For these reasons, most road agencies regularly monitor the levels of rut depths on

Hongzhi Wang

2005-01-01

270

Full-Depth Pavement Reclamation with Foamed Asphalt: Final Report  

Microsoft Academic Search

A comprehensive study on full-depth reclamation (FDR) of pavements with foamed asphalt has been completed for the California Department of Transportation by the University of California Pavement Research Center. A literature review revealed that very little research had been carried out on the reclamation of thick asphalt pavements (multiple overlays over a relatively weak base or subgrade). A mechanistic sensitivity

David Jones; P. Fu; John T Harvey; F. Halles

2008-01-01

271

Viscoelastic modelling for asphalt pavements - Software ViscoRoute  

Microsoft Academic Search

Huet-Sayegh model (1963) gives a set of constitutive equations of a visco-elastic material which accounts well for the behaviour of asphalt pavement layers, especially regarding thermal effects. This model allows rather good predictions of experimental data. The French pavement design method consists in a pavement mechanistic analysis based on the Burmister multilayer elastic model (1943) -LCPC software ALIZE (1982)-. In

A. Chabot; P. Tamagny; D. Poché; D. Duhamel

272

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

273

Acute whole body vibration training increases vertical jump and flexibility performance in elite female field hockey players  

PubMed Central

Objective: To quantify the acute effect of whole body vibration (WBV) training on arm countermovement vertical jump (ACMVJ), grip strength, and flexibility performance. Methods: Eighteen female elite field hockey players each completed three interventions of WBV, control, and cycling in a balanced random manner. WBV was performed on a Galileo machine (26 Hz) with six different exercises being performed. For the control, the same six exercises were performed at 0 Hz, whilst cycling was performed at 50 W. Each intervention was 5 min in duration with ACMVJ, grip strength, and flexibility measurements being conducted pre and post intervention. Results: There was a positive interaction effect (interventionxpre-post) of enhanced ACMVJ (p<0.001) and flexibility (p<0.05) parameters following WBV; however no changes were observed after the control and cycling interventions. There was no interaction effect for grip strength following the three interventions. Conclusions: Acute WBV causes neural potentiation of the stretch reflex loop as shown by the improved ACMVJ and flexibility performance. Additionally, muscle groups less proportionally exposed to vibration do not exhibit physiological changes that potentiate muscular performance.

Cochrane, D; Stannard, S

2005-01-01

274

Evaluation of Selected Softening Agents Used in Flexible Pavement Recycling.  

National Technical Information Service (NTIS)

Twenty-three softening agents were tested for physical and chemical properties. The agents were very low in viscosity, which seemed to correspond to a low asphaltenes content. Four of these softening agents were selected for detailed evaluation on two pav...

D. I. Anderson D. E. Peterson M. L. Wiley W. B. Betenson

1978-01-01

275

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

276

APPLICATION OF EMPIRICAL AND MECHANISTIC-EMPIRICAL PAVEMENT DESIGN PROCEDURES TO Mn\\/ROAD CONCRETE PAVEMENT TEST SECTIONS  

Microsoft Academic Search

Current pavement design procedures are based principally on empirical approaches. The introduction of new materials and the significant increase in traffic volumes have brought uncertainty to their prediction of pavement behavior. The current trend toward developing more mechanistic-empirical type pavement design methods led Minnesota to develop the Minnesota Road Research Project (Mn\\/ROAD). The project consists of 40 heavily instrumented test

T. R. Burnham

277

Team flexibility's relationship to staffing and performance in complex projects: An empirical analysis  

Microsoft Academic Search

We examine the role of flexibility in project team effectiveness. Specifically, we hypothesize that (1) it will mediate the relationship between staffing quality and effectiveness and (2) its relationship with team effectiveness will be moderated by project complexity, where more flexibility will be required when projects are complex. Hypotheses are tested using data collected from 60 cross-functional project teams. The

Sara A. McComb; Stephen G. Green; W. Dale Compton

2007-01-01

278

An empirical study of the relationships between IT infrastructure flexibility, mass customization, and business performance  

Microsoft Academic Search

Information technology (IT) infrastructure deserves serious attention from both the practitioner and academic communities, especially concerning the factors for IT infrastructure flexibility. The issue of flexibility is viewed as a critical aspect of IT infrastructure, because organizations are faced with an ever-increasing rate of change in their business environments. One effort most business sectors have made to prepare for this

Sock H. Chung; Terry Anthony Byrd; Bruce R. Lewis; F. Nelson Ford

2005-01-01

279

Investigation of frictional properties on wire combed PCC (Portland Cement Concrete) pavement surfaces  

NASA Astrophysics Data System (ADS)

This report involves PCC Pavements constructed with surface textures produced by a wide variety of wire combs. A small amount of testing was also performed on PCCP with other textures as a follow up of previous research on frictional properties. A limited amount of noise evaluation by rating panels and sound level (dbA) meters was conducted to assist in selection of an optimum the spacing for wire combs on future PCC Pavement projects. Included in this report is a brief description of each major project with summaries of friction number tests, standpatch texture depth tests, and sound level measurements.

1982-09-01

280

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

281

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...

282

Reduction of traffic and tire/pavement noise: 1st year results of the Arizona Quiet Pavement Program-Site III  

NASA Astrophysics Data System (ADS)

The Arizona Quiet Pavement Pilot Program overlaid major freeway segments in the Phoenix area with an Asphalt Rubber Friction Course (ARFC). The overlay was placed on various Portland Cement Concrete Pavement (PCCP) textures. Traffic noise reductions were evaluated by performing wayside traffic noise measurements and tire/pavement source level measurements. First year results for three different study sites are presented in this paper. Depending on the texture of the initial PCCP and microphone locations, reductions of up to 12 dBA in wayside traffic noise levels were measured. Similar reductions of tire/pavement source levels were measured. Results of the two methods are compared. Traffic conditions monitored during the measurements were modeled using the Federal Highway Administration's Traffic Noise Model (TNM 2.5) to compare modeled levels to those measured for PCCP and AFRC overlay conditions. The model under predicted levels for PCCP conditions and over predicted levels for AFRC conditions. The magnitude of under or over prediction varied with distance. The effect of propagation was examined and was aided by simultaneous measurements of wind conditions made by Arizona State University. TNM 2.5 was used to identify sound wall heights that were equivalent to the traffic noise reductions provided by the AFRC overlay.

Reyff, James A.; Donavan, Paul

2005-09-01

283

Improved performance of flexible amorphous silicon solar cells with silver nanowires  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

284

Development of a flexible laboratory testing platform for assessing steady-state and transient performance of WAMS  

Microsoft Academic Search

This paper analyzes the development of an experimental setup for the steady state and transient analysis of Wide Area Measurement Systems (WAMS). The flexibility of the generated input signals for which the PMU performance is assessed represents a novel contribution of the designed setup. Transient disturbances modeled by mathematical functions or extracted from simulated networks within DigSILENT PowerFactory software are

Alexandru Nechifor; Pawel Regulski; Deyu Cai; Vladimir Terzija

2011-01-01

285

High performance Ni-induced polySilicon Thin Film Transistors on Flexible PET substrates, suitable for display applications  

Microsoft Academic Search

High performance thin film transistors have been realized on flexible PET substrates. The crystallization of silicon film has been achieved using external mechanical stress assisted by a plasma hydrogenation technique. The formation of thin film transistors is possible by means of a lateral crystallization of amorphous silicon under the channel region. High mobility TFTs with an electron mobility of 25cm2\\/Vs

S. Paydavosi; A. Tamaddon; S. Mohajerzadeh

286

A graphene sheet exfoliated with microwave irradiation and interlinked by carbon nanotubes for high-performance transparent flexible electrodes  

Microsoft Academic Search

High quality graphene was obtained though microwave irradiated expansion following a solution process. This method is facile, inexpensive, and produces usable results. Ultrathin, uniform graphene films were fabricated at room temperature by a vacuum filtration method. Combining carbon nanotubes (CNTs) as bridges between graphene flakes allowed the fabrication of high-performance conductive films for flexible applications, with conductivities and optical properties

Guoqing Xin; Wontae Hwang; Namhun Kim; Sung M. Cho; Heeyeop Chae

2010-01-01

287

A graphene sheet exfoliated with microwave irradiation and interlinked by carbon nanotubes for high-performance transparent flexible electrodes.  

PubMed

High quality graphene was obtained though microwave irradiated expansion following a solution process. This method is facile, inexpensive, and produces usable results. Ultrathin, uniform graphene films were fabricated at room temperature by a vacuum filtration method. Combining carbon nanotubes (CNTs) as bridges between graphene flakes allowed the fabrication of high-performance conductive films for flexible applications, with conductivities and optical properties comparable to commercial ITO: 181 Omega sq(-1) at 82.2% transmittance after chemical treatment and doping. With future work, this versatile material could well provide an appropriate transparent electrode for flexible optical electronics. PMID:20823496

Xin, Guoqing; Hwang, Wontae; Kim, Namhun; Cho, Sung M; Chae, Heeyeop

2010-09-08

288

Numerical analysis of integral pavement\\/soil-wall structures in soft soil  

Microsoft Academic Search

In a country like the Netherlands, construction on weak and quite often wet soils is inevitable. The interaction between the pavement and the underlying foundation is then crucial to the overall construction performances. Focusing on this requirement, this contribution took an integrated approach in the analysis, including the development and implementation of constitutive models to capture the porosity and nonlinearity

Y. Zhao; X. Liu; A. Scarpas; C. Kasbergen; Arian de Bondt

2011-01-01

289

Contributions of PG Graded Asphalt to low Temperature Cracking Resistance of Pavement  

Microsoft Academic Search

The purpose of this research was to study and evaluate the role that asphalt binders play in the resistance of asphalt pavements to low temperature cracking. As part of the Strategic Highway Research Program (SHRP) new specifications for asphalt binders were developed that are based on the performance of the material. The asphalt binder graded and specified according to these

Ssu-Wei Loh; J. Olek

1999-01-01

290

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

291

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

PubMed

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

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

2012-11-26

292

The Performance Analysis of a Multi-Objective Immune Genetic Algorithm for Flexible Job Shop Scheduling  

Microsoft Academic Search

First, a multi-objective immune genetic algorithm integrating immune algorithm and genetic algorithm for flexible job shop\\u000a scheduling is designed. Second, Markov chain is used to analyze quantitatively its convergence. Third, a simulation experiment\\u000a of the flexible job shop scheduling is carried out. Running results show that the proposed algorithm can converge to the Pareto\\u000a frontier quickly and distribute evenly along

Xiuli Wu; Shudong Sun; Ganggang Niu; Yinni Zhai

2006-01-01

293

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

294

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

NASA Astrophysics Data System (ADS)

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

Plati, Christina; Georgiou, Panos; Loizos, Andreas

2013-04-01

295

GEOSYNTHETIC-REINFORCED PAVEMENT SYSTEM : TESTING & DESIGN  

Microsoft Academic Search

A large scale experimental program was presented in this paper, aimed at the improvement of the understanding, and evaluation of the structural contribution of geosynthetic reinforcement to pavement systems. The structural contribution of a geogrid was quantified by the increase in the layer coefficient of the base course material. Design parameters derived from the laboratory testing were analyzed and presented.

FILIPPO MONTANELLI

296

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

297

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

298

Reconstruction of a pavement geothermal deicing system  

SciTech Connect

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

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

1999-03-01

299

Multi-Scale Approach for Near-Surface Pavement Cracking and Failure Mechanism. USDOT Region V Regional University Transportation Center Final Report.  

National Technical Information Service (NTIS)

Near-surface cracking is one of the predominant distress types in flexible pavements. The occurrence of near-surface cracking, also sometimes referred to as top-down cracking, has increased in recent years with the increased construction of relatively thi...

C. Duarte H. Ozer I. L. Al-Qadi

2010-01-01

300

Training primary care physicians in flexible sigmoidoscopy--performance evaluation of 17,167 procedures.  

PubMed

The flexible fiber-optic sigmoidoscope is rapidly replacing the rigid sigmoidoscope in routine screening for colorectal cancer. This study was undertaken to evaluate the safety, usage pattern, and efficacy of fiber-optic sigmoidoscopy by evaluating the outcome of training and the results of procedures carried out by a group of primary care physicians. Of 1,153 participants in one-day flexible sigmoidoscopy workshops, 764 (66%) returned questionnaires evaluating their experiences following this training. Of these, 438 physicians had obtained a flexible sigmoidoscope, used it frequently, and had done a total of 17,167 examinations. The average time of scope usage was nine months. Although additional supervised training was suggested at the time of the workshop, 68% of physicians began doing flexible sigmoidoscopy without it. A total of 465 polyps and 153 cancers were detected by the study group for an overall detection rate of 2.7% for polyps and 0.9% for cancers. Four complications were reported. This study indicates that the technique of flexible sigmoidoscopy is readily learned, is diagnostically productive, and is reasonably safe in the hands of primary care physicians. PMID:3348037

Groveman, H D; Sanowski, R A; Klauber, M R

1988-02-01

301

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

302

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

303

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

304

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

305

Performance of recycled mixtures in State of Georgia. Final report  

Microsoft Academic Search

The Georgia Department of Transportation (GDOT) has been constructing recycled asphalt pavements routinely for about four years. This research project was undertaken to evaluate the performance of recycled pavements in comparison to virgin (control) asphalt pavements. Five projects, each consisting of a recycled section and a control section, were subjected to detailed evaluation. In-situ mix properties (such as percent air

P. S. Kandhal; S. S. Rao; B. Young

1994-01-01

306

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

307

Performance of HS-HR Flexible Foams in Small Open-flame Combustibility Tests  

Microsoft Academic Search

The development of small open-flame tests for measuring or predicting the combustibility characteristics of flexible polyurethane foams continues to be a subject of broad interest and active research. Notable recent activities in the residential furniture area include: (1) efforts by the California Bureau of Home Furnishings and Thermal Insulation to improve CAL TB 117; (2) work towards a national standard

Richard Skorpenske; Michael Blaszkiewicz; Michael Masciantonio

2004-01-01

308

On performance of an oscillating plate underwater propulsion system with variable chordwise flexibility at different depths of submergence  

NASA Astrophysics Data System (ADS)

In this work, an oscillating plate propulsor undergoing a combination of heave translation and pitch rotation is investigated experimentally. The oscillation kinematics are inspired by swimming mechanisms employed by fish and other marine animals. The primary focus was on the propulsive characteristics of such oscillating plates, which were studied by means of direct force measurements in the thrust-producing regime. Experiments were performed at constant Reynolds number and constant heave amplitude. By varying the Strouhal number, the depth of submergence and the chordwise flexibility of the plate, it was possible to investigate corresponding changes in the generated thrust and the hydromechanical efficiency. It was possible to establish a set of parameters, including the driving frequency of the system, the ratio of rigid to flexible segment length of the plate, and the range of Strouhal numbers that led to an overall increase in thrust and efficiency. The experiments, involving plates with various ratios of rigid to flexible segment lengths, showed that greater flexibility increased the propulsive efficiency and thrust compared to an identical motion of the purely rigid plate. By submerging the plate at different depths, it was observed that the proximity of the propulsor to the bottom of the channel led to an overall increase in the thrust coefficient across the oscillation frequencies considered. The flow visualization revealed the formation of large dynamic stall vortices that influenced the wake structure, and suggested that their constructive interaction with trailing edge vortices might lead to overall improvement of thrust and efficiency.

Barannyk, Oleksandr; Buckham, Bradley J.; Oshkai, Peter

2012-01-01

309

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

SciTech Connect

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

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

1995-05-01

310

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

PubMed

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

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

2013-04-04

311

High performance, flexible polymer light-emitting diodes (PLEDs) with gravure contact printed hole injection and light emitting layers  

Microsoft Academic Search

The ultimate approach to organic semiconductor device fabrication is expected to be via high-speed, large area, roll-to-roll (R2R) printing. Gravure contact printing is one of the highest volume potential techniques, operating at speeds of over 35m\\/min. Here we report high performance, flexible polymer light-emitting diodes (PLEDs) with gravure contact printed hole injection and emissive layers. We are able to successfully

Dae-Young Chung; Jingsong Huang; Donal D. C. Bradley; Alasdair J. Campbell

2010-01-01

312

Covariance matrix adaptation evolution strategy for pavement backcalculation  

Microsoft Academic Search

The falling weight deflectometer (FWD) is the foremost and widely accepted tool for characterizing the deflection basins of pavements in a non-destructive manner. The FWD pavement deflection data are used to determine the in situ mechanical properties (elastic moduli) of the pavement layers through inverse analysis, a process commonly referred to as backcalculation (B\\/C). Several B\\/C methodologies have been proposed

Kasthurirangan Gopalakrishnan; Anshu Manik

2010-01-01

313

Variability of pavement noise benefit by vehicle type  

Microsoft Academic Search

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

Judith L. Rochat; David R. Read

2005-01-01

314

Polyaniline nanowire arrays aligned on nitrogen-doped carbon fabric for high-performance flexible supercapacitors.  

PubMed

A combination of vertical polyaniline (PANI) nanowire arrays and nitrogen plasma etched carbon fiber cloths (eCFC) was fabricated to create 3D nanostructured PANI/eCFC composites. The small size of the highly ordered PANI nanowires can greatly reduce the scale of the diffusion length, allowing for the improved utilization of electrode materials. A two-electrode flexible supercapacitor based on PANI/eCFC demonstrates a high specific capacitance (1035 F g(-1) at a current density of 1 A g(-1)), good rate capability (88% capacity retention at 8 A g(-1)), and long-term cycle life (10% capacity loss after 5000 cycles). The lightweight, low-cost, flexible composites are promising candidates for use in energy storage device applications. PMID:23984643

Yu, Pingping; Li, Yingzhi; Yu, Xinyi; Zhao, Xin; Wu, Lihao; Zhang, Qinghua

2013-09-13

315

Performance analysis of flexible material handling systems for the apparel industry  

Microsoft Academic Search

Flexible material handling systems (FMHS) have been widely used to enhance productivity involved with product proliferation,\\u000a and thus far, only fixed-track material handling systems such as Eton systems in the apparel industry are commonly used. This\\u000a paper explores the potential advantages of a FMHS using free-ranging automated-guided vehicles with a local positioning system\\u000a for the apparel industry. First, the free-ranging

James B. Dai; Neville K. S. Lee; W. S. Cheung

2009-01-01

316

A review of thermoregulation and physiological performance in reptiles: what is the role of phenotypic flexibility?  

Microsoft Academic Search

Biological functions are dependent on the temperature of the organism. Animals may respond to fluctuation in the thermal environment\\u000a by regulating their body temperature and by modifying physiological and biochemical rates. Phenotypic flexibility (reversible\\u000a phenotypic plasticity, acclimation, or acclimatisation) in rate functions occurs in all major taxonomic groups and may be\\u000a considered as an ancestral condition. Within the Reptilia, representatives

Frank Seebacher

2005-01-01

317

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

NASA Astrophysics Data System (ADS)

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.

Fang, Run-Chen; Sun, Qing-Qing; Zhou, Peng; Yang, Wen; Wang, Peng-Fei; Zhang, David Wei

2013-02-01

318

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

PubMed

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

Fang, Run-Chen; Sun, Qing-Qing; Zhou, Peng; Yang, Wen; Wang, Peng-Fei; Zhang, David Wei

2013-02-19

319

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

320

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

PubMed

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

Kwak, Kiyeol; Cho, Kyoungah; Kim, Sangsig

2013-09-27

321

Structural control of a flexible satellite bus for improved jitter performance  

NASA Astrophysics Data System (ADS)

The increasing demand for global communications and limitations on RF communications bandwidth has driven several constellations to baseline laser cross-links between the satellites within their constellations. The use of laser communications over a long distance dictates the need for accurate pointing and jitter suppression in order to maintain signal continuity. Vibrations upon a satellite bus or orbit come from several sources including: momentum systems, flexible appendages, motors and cryocoolers. Attenuation of these vibrations requires a combination of disturbance reduction, disturbance isolation, payload isolation, input command shaping, appendage damping and passive/active bus structural control. This paper addresses these techniques in a systems approach to satellite structural control. Experimental results from a representative flexible satellite truss structure using a series of integral D-Strut structural dampers is presented. The passive damping system is used to reduce resonant amplification of disturbances on precision optical equipment jitter. The use of different combinations of longitudinal, transverse and diagonal dampers is discussed to achieve specific modal damping. In addition, the design of the integral truss dampers is discussed along with their application to satellite bus construction.

Jacobs, Jack H.; Hyde, T. Tupper; Boyd, Jim; Hadden, Steve; Davis, L. Porter

1998-06-01

322

Use of artificial living system for pavement distress survey  

Microsoft Academic Search

Automation of pavement surface distress survey is of considerable interest since it facilitates road maintenance. Pavement distress detection algorithm is proposed, which includes preprocessing and artificial life algorithm. In nature, bee population consists of different species of bees. Different species of bees cooperate with others and build combs. The process of building combs is based on a bottom-up structure instead

H. G. Zhang; Q. Wang

2004-01-01

323

A NEW APPROACH TO PAVEMENT DESIGN USING LIME STABILISED SUBGRADES  

Microsoft Academic Search

This paper outlines various design procedures that have been known to be used and some of the shortcomings in their approach to specify suitable material properties and layer thickness. Each procedure provides a slightly different solution. The aim of this paper to propose a new design approach using either a mechanistic or empirical pavement analysis methods to find the pavement

George Vorobieff; Greg Murphy

2003-01-01

324

Wavelet-based pavement distress detection and evaluation  

Microsoft Academic Search

An automated pavement inspection system consists of image acquisition and distress image processing. The former is accomplished with imaging sensors, such as video cameras and photomultiplier tubes. The latter includes distress detection, isolation, classification, evaluation, segmentation, and compression. We focus on wavelet-based distress detection, isolation, and evaluation. After a pavement image is decomposed into different-frequency subbands by the wavelet transform,

Jian Zhou; Peisen S. Huang; Fu-Pen Chiang

2006-01-01

325

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...

326

Permeable pavement demonstration site at Edison Environmental Center (Presentation)  

EPA Science Inventory

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

327

Network-Level Deflection Data Collection for Rigid Pavements.  

National Technical Information Service (NTIS)

The existing rigid pavement deflection data contained in the PES database are evaluated and found to be inadequate for any network-level study of the structural behavior of rigid pavements. The PES data were evaluated by comparing them with existing data ...

E. Perrone T. Dossey W. R. Hudson

1994-01-01

328

Paperless Pavement Condition Rating System Development. (Includes Executive Summary).  

National Technical Information Service (NTIS)

The Pavement Condition Rating (PCR) system has been used by Ohio DOT as a means of establishing non-routine maintenance needs on highway sections for over 10 years. The PCR system develops a numerical rating for a segment of pavement which reflects the se...

J. C. Gilfert K. F. Conner

1996-01-01

329

Subgrade Temperature and Freezing Cycles in Pervious Pavements  

Microsoft Academic Search

With the construction of four new test cells in 2008, the Minnesota Department of Transportation (Mn\\/DOT) now has six unique pervious pavement test sections at the MnROAD test facility. Recorded temperatures in the pervious pavements and subgrades were compared to impervious Portland Cement Concrete (PCC) test sections over the same time interval. It was found that the subgrade in pervious

R. J. Rohne; M. A. Lebens

330

Comparison of test specimen preparation techniques for pervious concrete pavements  

Microsoft Academic Search

The objective of this study was to evaluate different pervious concrete test specimen preparation techniques in an effort to produce specimens having properties similar to in-place pervious concrete pavement. Cylinders and slabs were cast using pervious concrete from three different paving projects using different procedures. The comparisons of cast specimens to pavement cores were based on infiltration rate, density, and

Bradley J. Putman; Andrew I. Neptune

2011-01-01

331

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

332

Real-time measurement and high-speed identification of highway pavement surface deformation  

Microsoft Academic Search

Pavement distress status is very important to investigate and evaluate pavement condition, which is characterized by distress types, degree and area. The measurement of three dimensions structure of pavement surface is of great value for the judgment of pavement distress status. Optical three dimensional profilometry is a well established technique for the measurement of three dimensions surface profiles, which has

Lin Fu; Anzhi He; Zhenhua Li

2006-01-01

333

Airport pavement roughness evaluation based on aircraft response  

NASA Astrophysics Data System (ADS)

Runway roughness affects primarily ride quality and dynamic wheel loads. The forces applied onto the airport pavement by aircraft vary instantaneously above and blow the static weight, which in turn increase the runway roughness. One method to effectively assess the ride quality of the airport runway is to measure its longitudinal profile and numerical simulate aircraft response performing a takeoff, landing or taxiing on that profile data. In this study the aircraft responses excited as the aircraft accelerates or moves at a constant speed on the runway during takeoff and taxi are computed by using the improved computer program TAXI. This procedure is capable of taking into account both the effects of discrete runway bumps and runway roughness. Thus, sections of significant dynamic response can be determined, and the maintenance and rehabilitation works for airport runways will be conducted.

Dong, Qinxi; Hachiya, Yoshitaka; Endo, Katsura; Himeno, Kenji; Kawamura, Akira; Matsui, Kunihito

2004-07-01

334

Pavement damage model incorporating vehicle dynamics and a 3D pavement surface  

Microsoft Academic Search

This paper proposes a mechanistic-empirical pavement damage model to predict changes in 3D road profiles due to dynamic axle loads. The traffic is represented by a fleet of quarter cars which allows for statistical variability in model parameters such as velocity, suspension stiffness, suspension damping, sprung mass, unsprung mass and tyre stiffness. The fleet model generates statistical distributions of dynamic

A. Taheri; E. J. OBrien; A. C. Collop

2012-01-01

335

The influence of low-order chord-wise flexibility on the performance of a flapping wing  

NASA Astrophysics Data System (ADS)

The aerodynamic role of flexible fight structures in airborne creatures is still poorly understood. The objective of this study is to distill the basic phenomena of flapping with deformable wings for their use in the efficient design of bio-inspired flight vehicles. The target of the study is a two-dimensional wing with rigid components connected by damped torsion springs. This simplified structure reduces the complexity of the problem, while retaining the leading-order influence of wing flexion. The motion of the leading portion of the wing is prescribed with hovering-type kinematics, while the trailing portions respond passively. Numerical simulations are performed with a viscous vortex particle method with strongly-coupled structural dynamics. The investigation focuses on the influences of several key parameters: spring stiffness (from rigid to very flexible), the location of axis of rotation, and the timing between the rotational and translational components of the kinematics. The effects are quantified via several performance measures, including production of mean and rms lift, the mean consumption of power, and the lift per unit power. Some important correlations are identified between the input parameters and the performance metrics, the passive wing deflection and the wake structure. It is shown that variation in the rotation phase lead are accompanied by topological changes in the wake vortex dynamics.

Toomey, Jonathan; Eldredge, Jeff D.

2008-11-01

336

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

PubMed

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

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

2012-05-22

337

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

SciTech Connect

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

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

1994-10-01

338

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

ERIC Educational Resources Information Center

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

Cason, Gerald J.; And Others

339

Development of fiber Bragg-grating-based soil pressure transducer for measuring pavement response  

Microsoft Academic Search

A soil pressure transducer by using fiber Bragg grating (FBG) sensors associated with a circular diaphragm is developed. The FBG based transducers can be used for pavement performance study and weigh-in-motion measurement. We consider three methods of bonding the FBG to the diaphragm: (1) radially, (2) radially, inside a glass capillary, and (3) circumferentially. The investigation of strain-gradient induced spectral

Chia-Chen Chang; Gregg Johnson; Sandeep T. Vohra; Bryan Althouse

2000-01-01

340

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

2013-08-03

341

Simultaneous effects of salted water and water flow on asphalt concrete pavement deterioration under freeze–thaw cycles  

Microsoft Academic Search

The presence of water flow on road surfaces may lead to early deterioration of bituminous pavements. The adverse impacts of various anti-freezing materials on road surface performance have drawn the attention of many researchers. However, the simultaneous effects of salted water and water flow on the deterioration of road surfaces, particularly under freeze–thaw conditions, have not been adequately addressed. This

Behnam Amini; Saleh Sharif Tehrani

2012-01-01

342

Pavement cracking measurements using 3D laser-scan images  

NASA Astrophysics Data System (ADS)

Pavement condition surveying is vital for pavement maintenance programs that ensure ride quality and traffic safety. This paper first introduces an automated pavement inspection system which uses a three-dimensional (3D) camera and a structured laser light to acquire dense transverse profiles of a pavement lane surface when it carries a moving vehicle. After the calibration, the 3D system can yield a depth resolution of 0.5 mm and a transverse resolution of 1.56 mm pixel-1 at 1.4 m camera height from the ground. The scanning rate of the camera can be set to its maximum at 5000 lines s-1, allowing the density of scanned profiles to vary with the vehicle's speed. The paper then illustrates the algorithms that utilize 3D information to detect pavement distress, such as transverse, longitudinal and alligator cracking, and presents the field tests on the system's repeatability when scanning a sample pavement in multiple runs at the same vehicle speed, at different vehicle speeds and under different weather conditions. The results show that this dedicated 3D system can capture accurate pavement images that detail surface distress, and obtain consistent crack measurements in repeated tests and under different driving and lighting conditions.

Ouyang, W.; Xu, B.

2013-10-01

343

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

344

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

SciTech Connect

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

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

1995-07-01

345

Pavement Marking Paints: Two Studies.  

National Technical Information Service (NTIS)

The document reports on two studies. The first involves the performance of modified alkyd and modified alkyd-chlorinated rubber yellow traffic marking paints, utilizing normal-lead-silico-chromate in lieu of or in combination with the more commonly used m...

J. G. F. Hiss J. T. Capelli D. R. Brewster

1970-01-01

346

Performance Test of a New Wet ESP with Flexible Collection Electrodes  

Microsoft Academic Search

Wet electrostatic precipitator (WESP) has been modernized over the last few decades. They were suitable for controlling slurry droplet, fine particles and acid aerosols. However, the applicability of current wet precipitators was badly limited for the imperfect mode of water film generation, back-corona, higher power consumption, corrosion of the collector surfaces. Tests were performed to investigate the performance of WESP

Chang Jingcai; Dong Yong; Yan Jun; Li Bing; Ma Chunyuan

2010-01-01

347

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

348

Cost-Effectiveness Analysis of Enhancing the Pavement-Related Information Systems at the Texas Department of Transportation.  

National Technical Information Service (NTIS)

Research Project 0-4186 entitled, 'Cradle-to-Grave Monitoring of Pavements and Pavement Management Information System (PMIS) Functionality Enhancement Planning,' is intended to develop strategic plans for integrating the pavement-related databases at the ...

A. Karoonsoontawong Z. Zhang R. B. Machemehl

2003-01-01

349

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

350

Improving accuracy and flexibility of ASTM D 5470 for high performance thermal interface materials  

Microsoft Academic Search

The thermal demands of current and next generation microprocessors have driven requirements for thermal interface materials (TIMs) to the point where reliable vendor data is often not available. Vendors are struggling to meet customers needs. Existing industry test standards were intended for electrical insulation materials and cannot provide accurate data for todays high performance TIMs. Manufacturers are forced to accept

D. Kearns

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

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

Microsoft Academic Search

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

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

2000-01-01

353

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

354

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

355

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

356

ANALYSIS OF GROUP MAINTENANCE STRATEGY -ROAD PAVEMENT AND SEWERAGE PIPES-  

NASA Astrophysics Data System (ADS)

Recently, it is critical to manage deteriorating sewerage and road facilities efficiently and strategically. Since the sewerage pipes are mostly installed under road pavement, the works for the replacement of the sewerage pipes are partially common to the works for the road. This means that the replacement cost can be saved by coordinating the timing of the replacements by sewerage pipe and road pavement. The purpose of the study is to develop the model based on Markov decision process to derive the optimal group maintenance policy so as to minimize lifecycle cost. Then the model is applied to case study area and demonstrated to estimate the lifecycle cost using statistical data such as pipe replacement cost, road pavement rehabilitation cost, and state of deterioration of pipes and road pavement.

Tanimoto, Keishi; Sugimoto, Yasuaki; Miyamoto, Shinya; Nada, Hideki; Hosoi, Yoshihiko

357

Condition of Longitudinal Steel in Illinois Continuously Reinforced Concrete Pavements.  

National Technical Information Service (NTIS)

An investigation was made of several CRC pavements constructed within Illinois to determine the extent of corrosion occurring on the longitudinal reinforcement at transverse cracks. The effect of crack width, crack spacing, depth of reinforcement, slab th...

J. S. Dhamrait F. K. Jacobsen D. R. Schwartz

1973-01-01

358

Linear Lighting System for Automated Pavement Distress Measurement.  

National Technical Information Service (NTIS)

The artificial lighting system is a specially designed lighting device for the automated pavement distress measurement system (VCrack) developed in a previous Texas Department of Transportation project. The basic function of this device is to provide inte...

B. Xu

2006-01-01

359

Chip Seals, Friction Courses, and Asphalt Pavement Rutting, 1990.  

National Technical Information Service (NTIS)

Contents: Washington State chip seal study; Friction courses for moderate traffic highways; Chip seals for high traffic pavements; Improving durability of open-graded friction courses; Estimating voids in a double chip seal; Correlation between field and ...

N. C. Kassabian A. G. Tobias L. Crayton K. Solomon N. Solomon

1990-01-01

360

Automated Real-Time Pavement Crack Detection and Classification System.  

National Technical Information Service (NTIS)

Statistics published by the Federal Highway Administration indicate that the maintenance and rehabilitation of highway pavement in the United States requires over 17 billion dollars per year. Currently, maintenance and repairs account for nearly one-third...

C. Glazier H. D. Cheng

2007-01-01

361

Implementation of Mechanistic Pavement Design: Field and Laboratory Implementation.  

National Technical Information Service (NTIS)

One of the most important parameters needed for 2002 Mechanistic Pavement Design Guide is the dynamic modulus (E*). The dynamic modulus (E*) describes the relationship between stress and strain for a linear viscoelastic material. The E* is the prime mater...

A. Maher N. Gucunski T. Bennert

2005-01-01

362

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

363

Prediction of Hydroplaning Potential from Runoff Characteristics of Highway Pavements.  

National Technical Information Service (NTIS)

A computer program, HYDROP, was developed to predict hydroplaning potential resulting from uniform rainfall of any intensity on sections of highway pavement with varying degrees of topographic irregularity. The program uses a kinematic-wave approximation ...

J. R. Reed D. F. Kibler R. S. Heubner G. W. Marks

1985-01-01

364

Long-Life Concrete Pavements in Europe and Canada.  

National Technical Information Service (NTIS)

Long-life concrete pavements require less frequent repair and rehabilitation and contribute to highway safety and congestion mitigation. The Federal Highway Administration, American Association of State Highway and Transportation Officials, and National C...

A. Correa D. Dawood K. Hall R. Tally S. Vanikar T. Cackler

2007-01-01

365

Pavement Rehabilitation, Strength and Deformation Characteristics, and Surface Properties, 2005.  

National Technical Information Service (NTIS)

TRBs Transportation Research Record: Journal of the Transportation Research Board 1905 examines pavement rehabilitation in areas such as monitoring, cold in-place recycling, application of the reliability concept, treatments, reflective crack relief, and ...

2005-01-01

366

Pervious Pavements: Installation, Operations and Strength. Part 1: Pervious Concrete.  

National Technical Information Service (NTIS)

Pervious pavement systems are now being recognized as a best management practice by the Environmental Protection Agency and the state of Florida. The pervious concrete system is designed to have enhanced pore sizes in the surface layer compared to convent...

E. Stuart I. Uju M. Chopra M. Hardin M. Wanielista

2011-01-01

367

Finite Element Evaluation of Pervious Concrete Pavement for Roadway Shoulders.  

National Technical Information Service (NTIS)

Pervious concrete has provided an effective solution for storm runoff for parking lots, sidewalks, bike trails, and other applications. It should be readily adaptable for use on roadway shoulders. Being a relatively new material for use in pavement for ro...

A. Alam L. Haselbach W. Cofer

2011-01-01

368

Evaluation of Reclaimed Asphalt Pavement for Surface Mixtures.  

National Technical Information Service (NTIS)

Indiana Department of Transportation (INDOT) has successfully used Reclaimed Asphalt Pavement (RAP) for decades because of its economic and environmental benefits. However, until recently, INDOT has disallowed the use of RAP in asphalt surface mixtures be...

A. Shah K. J. Kowalski R. S. McDaniel

2012-01-01

369

Skid Resistance of Pavement Marking Materials: Volume I.  

National Technical Information Service (NTIS)

The skid resistance of typical pavement marking materials is determined. A data base of full-scale locked-wheel skid resistance is presented for typical traffic paints of various formulations, hot spray and extruded thermoplastics, cold preformed plastics...

D. A. Anderson G. F. Hayhoe J. J. Henry

1981-01-01

370

Methodology for Flexible and Efficient Analysis of the Performance of Page Segmentation Algorithms  

Microsoft Academic Search

This paper presents part of a new DIA performance analysis framework aimed at Layout Analysis algorithm developers. A new region-representation scheme (an interval-based description of isothetic polygons) and a corresponding comparison approach are introduced. These enable fast and accurate geometric comparison of ground-truth with results of page segmentation, improving on current evaluation methods. Complex layouts are accurately described and Layout

Apostolos Antonacopoulos; A. Brough

1999-01-01

371

Flexibility in Japanese internal labour markets: The introduction of performance-related pay  

Microsoft Academic Search

The introduction of performance-related pay by Japanese firms, a development known as seikashugi, stands out as the most important adjustment in their management of regular employees. This paper discusses this development\\u000a and analyses its implications for the logic of Japanese employment practices. Previous analyses and developments in other\\u000a countries suggest that it could imply a breakdown of the internal labour

Arjan Bernhard Keizer

2011-01-01

372

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

NASA Astrophysics Data System (ADS)

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

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

2001-12-01

373

Life Cycle Cost Analysis for INDOT Pavement Design Procedures  

Microsoft Academic Search

Given the aging of highway pavements, high traffic levels, and uncertainty of sustained preservation funding, there is a need for balanced decision-making tools such as LCCA to ensure long-term and cost-effective pavement investments. With driving forces such as ISTEA 1991, the NHS Act of 1995, and TEA-21, LCCA enables evaluation of overall long-term economic efficiency between competing alternative investments and

Geoffery Lamptey; Muhammad Z. Ahmad; Samuel Labi; Kumares C. Sinha

2005-01-01

374

High-Performance Flexible a-IGZO TFTs Adopting Stacked Electrodes and Transparent Polyimide-Based Nanocomposite Substrates  

Microsoft Academic Search

We demonstrated flexible amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) on fully transparent and high-temperature polyimide-based nanocomposite substrates. The flexible nanocomposite substrates were coated on the carrier glass substrates and were debonded after the TFT microfabrication. The adoption of the Ti\\/IZO stacked electrodes as source\\/drain\\/ gain electrodes significantly improved the etching compatibility with other material layers, enabling successful implementation of flexible

Chih-Wei Chien; Cheng-Han Wu; Yu-Tang Tsai; Yen-Cheng Kung; Chang-Yu Lin; Po-Ching Hsu; Hsing-Hung Hsieh; Chung-Chih Wu; Yung-Hui Yeh; Chyi-Ming Leu; Tzong-Ming Lee

2011-01-01

375

Concrete Pavement Technology Program: Evaluating the Use of Fiber-Reinforced Polymer Bars in Continuously Reinforced Concrete Pavement.  

National Technical Information Service (NTIS)

This TechBrief discusses the potential use of fiber-reinforced polymer (FRP) bars in continuously reinforced concrete pavements (CRCP). Relative advantages and disadvantages of FRP bars are presented, and some specific considerations for the use of FRP ba...

2009-01-01

376

Fourth Cycle of Pavement Research at the Pennsylvania Transportation Research Facility. Volume 7. Fourth Cycle of Pavement Research Summary Report.  

National Technical Information Service (NTIS)

The fourth cycle of research at the Pennsylvania Transportation Institute's Pennsylvania Transportation Research Facilities involved the evaluation of the structural behavior of a variety of bituminous and portland cement pavement materials, including ope...

D. A. Anderson W. P. Kilareski D. R. Luhr

1984-01-01

377

Flexible CoAl LDH@PEDOT core/shell nanoplatelet array for high-performance energy storage.  

PubMed

A CoAl-layered double hydroxide (LDH)@poly(3,4-ethylenedioxythiophene) (PEDOT) core/shell nanoplatelet array (NPA) is grown on a flexible Ni foil substrate as a high-performance pseudocapacitor. The LDH@PEDOT core/shell NPA shows a maximum specific capacitance of 649 F/g (based on the total mass) by cyclic voltammetry (scan rate: 2 mV/s) and 672 F/g by galvanostatic discharge (current density: 1 A/g). Furthermore, the hybrid NPA electrode also exhibits excellent rate capability with a specific energy of 39.4 Wh/kg at a current density of 40 A/g, as well as good long-term cycling stability (92.5% of its original capacitance is retained after 5000 cycles). These performances are superior to those of conventional supercapacitors and LDH NPA without the PEDOT coating. The largely enhanced pseudocapacitor behavior of the LDH@PEDOT NPA electrode is related to the synergistic effect of its individual components: the LDH nanoplatelet core provides abundant energy-storage capacity, while the highly conductive PEDOT shell and porous architecture facilitate the electron/mass transport in the redox reaction. PMID:22961997

Han, Jingbin; Dou, Yibo; Zhao, Jingwen; Wei, Min; Evans, David G; Duan, Xue

2012-09-10

378

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

Code of Federal Regulations, 2013 CFR

...HIGHWAYS NATIONAL PARK SERVICE MANAGEMENT SYSTEMS National Park Service Management Systems § 970.208 Federal lands pavement management system (PMS). In addition...A) Identifies alternative strategies to improve pavement...

2013-04-01

379

Long-Term Pavement Monitoring: Colorado's Evaluation of the Pilot Case Study.  

National Technical Information Service (NTIS)

The report documents Colorado's involvement in the Long-term Pavement Monitoring pilot case study. Besides the data collection procedure that was recommended by FHWA, Colorado investigated the current network level pavement monitoring program, which consi...

W. Hutter

1984-01-01

380

Pavement Quality Indicators. Five Year Report (2009-2013) for the Nebraska Department of Roads.  

National Technical Information Service (NTIS)

The Nebraska Department of Roads (NDOR) conducts an annual examination of pavement conditions on Nebraska's interstate and federal highway system. During these examinations, indicators of pavement quality are measured directly or compiled from parameters ...

C. Villaneueva W. Jensen

2013-01-01

381

Development of an Automated Procedure for Implementing Resilient Modulus Test for Design of Pavement.  

National Technical Information Service (NTIS)

The resilient modulus (MR) of pavement materials is an essential parameter for mechanistically based pavement design procedure. A resilient modulus database, Soil Lab Assistant (SLA) was developed to store the available MR test results and to facilitate s...

W. V. Ping Z. Yang

2005-01-01

382

Impact of Airport Pavement Deicing Products on Aircraft and Airfield Infrastructure. A Synthesis of Airport Practice.  

National Technical Information Service (NTIS)

Airfield pavement deicing and anti-icing are essential activities to maintain safe winter operations of the aviation industry. Airfield pavement deicing products (PDPs) traditionally consisting of urea or glycols have become less popular owing to their ad...

X. Shi

2008-01-01

383

Producing Durable Continuously Reinforced Concrete Pavement using Glass- ceramic Coated Reinforcing Steel.  

National Technical Information Service (NTIS)

PRESENTATION: The Corrosion Problem in Pavements * Nature of the Vitreous-Ceramic Coating * Ease of Application to Reinforcement Steel * Bond Strength and Corrosion-Resistance * Field Demonstration Program * Testing in Reinforced Concrete Pavement * Summa...

B. A. Williams J. C. Weiss M. Koenigstein P. G. Malone S. W. Morefield

2010-01-01

384

Application of Full-Scale Accelerated Pavement Testing. A Synthesis of Highway Practice.  

National Technical Information Service (NTIS)

This synthesis, which describes the state of the practice for full-scale accelerated pavement testing (APT), will be of interest to state department of transportation (DOT) pavement design and materials engineers; DOT research staff, including field and l...

J. B. Metcalf

1996-01-01

385

Stabilization of Existing Subgrades to Improve Constructibility during Interstate Pavement Reconstruction. A Synthesis of Highway Practice.  

National Technical Information Service (NTIS)

This synthesis will be of interest to state DOT construction, geotechnical, materials, and pavement system design engineers, engineering geologists, and research engineers, and others concerned with the constructibility of new pavements over existing subg...

J. G. Laguros G. A. Miller

1997-01-01

386

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

387

Material Selection and Design Consideration for Moisture Damage of Asphalt Pavement.  

National Technical Information Service (NTIS)

Moisture damage is a primary mode of distress occurring in Nebraska hot mix asphalt (HMA) pavements. The use of hydrated lime has been recommended for Nebraska HMA pavements to mitigate moisture-related damage. There are several techniques of introducing ...

J. E. S. Lutif Y. Kim

2006-01-01

388

Enhancement of Resilient Modulus Data for the Design of Pavement Structures in Florida.  

National Technical Information Service (NTIS)

The resilient modulus (MR) of pavement materials is an essential parameter for mechanistically based pavement design procedures. However, measuring the resilient modulus of a particular site has been a complex and difficult task. The process, as outlined ...

C. C. Ling W. V. Ping

2007-01-01

389

Evaluating the Effect of Slab Curling on IRI for South Carolina Concrete Pavements.  

National Technical Information Service (NTIS)

Concrete pavements are known to curl due to a temperature gradient within the concrete caused by both daily and seasonal temperature variations. This research project measured the magnitude of concrete pavement slab curling of two newly constructed jointe...

A. M. Johnson B. C. Smith L. W. Gibson W. H. Johnson

2010-01-01

390

Development of an In situ Method for Continuous Evaluation of the Resilient Modulus of Pavement Subgrade.  

National Technical Information Service (NTIS)

Pavement designs, materials and uses vary around the world, but engineers typically employ the resilient moduli of pavement materials as the primary means of evaluating those materials. Unfortunately, the majority of tests used to determine the resilient ...

M. P. Rits

1992-01-01

391

Flexible Polyurethane .  

National Technical Information Service (NTIS)

Flexible polyurethane foam systems with different densities and load-bearing properties have been developed for use in packaging applications. A flexible foam formulation, Number 092674-1, has been designated BKC 45301 according to Material Standard 21706...

J. Salary

1976-01-01

392

'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

2013-10-24

393

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

394

Flexible high-performance all-inkjet-printed inverters: organo-compatible and stable interface engineering (adv. Mater. 34/2013).  

PubMed

On page 4773 Yongtaek Hong, Hoichang Yang, and co-workers demonstrate high-performance, flexible, all-inkjet-printed organic thin-film transistor (OTFT) inverters showing full up-down switching. They are implemented by introducing organic-compatible, hydroxylfree, end-functionalized polystyrene at the interfaces of the channel and source/drain contact. PMID:24019137

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

2013-09-14

395

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

396

DEVELOPING A TRACK MODEL FOR TESTING THE ROAD PAVEMENT UNDER REPEATED MOVING SURFACE LOADS  

Microsoft Academic Search

It is not uncommon to see road pavement damage in areas near road intersections. One type of pavement failure found on major roads appears to be caused by frequent decelerations and accelerations of heavy vehicles near signalized intersections. The effects of such repeated surface tractions on road pavement have not been widely studied yet. Proposed in this paper is the

Jim Shiau; Tagarajan Perumal; Michael Benjamin; Selvan Pather; Ron Ayers

397

Applying Data Mining Technique to Compute LDE for Rutting Through Full Scale Accelerated Pavement Testing  

Microsoft Academic Search

Results from closely controlled full-scale Accelerated Pavement Testing (APT) were employed to establish a rutting prediction model using the “Find Laws” data mining technique. Seven test pavements (264 records) from the Cold Regions Research and Engineering Laboratory's (CRREL's) Heavy Vehicle Simulator (HVS) and one test pavement including 8 records from the Texas Department of Transportation's (TxDOT's) Mobile Load Simulator (MLS)

Tung-Tsan Chen; Jia-Ruey Chang; Dar-Hao Chen

2008-01-01

398

Evaluation of Grade and Straightedge Tolerances in Federal Aviation Administration Pavement Construction Specifications  

Microsoft Academic Search

Federal Aviation Administration (FAA) specifications for runway, taxiway, and apron pavements contain acceptance criteria based on grade and straightedge tolerances (1). Recent specifications have focused on measured profile indices as a primary acceptance measure for pavement smoothness during construction. The FAA recognizes this and funds research into runway pavement ride quality with the goal of quantifying smoothness acceptance criteria. The

Jeffrey Rapol

399

High-Performance Large-Scale Flexible Dye-Sensitized Solar Cells Based on Anodic TiO2 Nanotube Arrays.  

PubMed

A simple strategy to fabricate flexible dye-sensitized solar cells involves the use of photoanodes based on TiO2 nanotube (TNT) arrays with rear illumination. The TNT films (tube length ?35 ?m) were produced via anodization, and sensitized with N719 dye for photovoltaic characterization. Pt counter electrodes of two types were used: a conventional FTO/glass substrate for a device of rigid type and an ITO/PEN substrate for a device of flexible type. These DSSC devices were fabricated into either a single-cell structure (active area 3.6 × 0.5 cm(2)) or a parallel module containing three single cells (total active area 5.4 cm(2)). The flexible devices exhibit remarkable performance with efficiencies ? = 5.40 % (single cell) and 4.77 % (parallel module) of power conversion, which outperformed their rigid counterparts with ? = 4.87 % (single cell) and 4.50 % (parallel model) under standard one-sun irradiation. The flexible device had a greater efficiency of conversion of incident photons to current and a broader spectral range than the rigid device; a thinner electrolyte layer for the flexible device than for the rigid device is a key factor to improve the light-harvesting ability for the TNT-DSSC device with rear illumination. Measurements of electrochemical impedance spectra show excellent catalytic activity and superior diffusion characteristics for the flexible device. This technique thus provides a new option to construct flexible photovoltaic devices with large-scale, light-weight, and cost-effective advantages for imminent applications in consumer electronics. PMID:24050628

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

2013-10-04

400

H-TiO(2) @MnO(2) //H-TiO(2) @C core-shell nanowires for high performance and flexible asymmetric supercapacitors.  

PubMed

A flexible solid-state asymmetric supercapacitor device with H-TiO(2) @MnO(2) core-shell NWs as the positive electrode and H-TiO(2) @C core-shell NWs as the negative electrode is developed. This device operates in a 1.8 V voltage window and is able to deliver a high specific capacitance of 139.6 F g(-1) and maximum volumetric energy density of 0.30 mWh cm(-3) with excellent cycling performance and good flexibility. PMID:23080535

Lu, Xihong; Yu, Minghao; Wang, Gongming; Zhai, Teng; Xie, Shilei; Ling, Yichuan; Tong, Yexiang; Li, Yat

2012-10-19

401

Nanoparticles-modified polymer-based solar-reflective coating as a cooling overlay for asphalt pavement  

Microsoft Academic Search

The phenomenon of rutting is one of the most serious problems on asphalt pavements. Decreasing the surface temperature of the asphalt pavement is an effective method to solve the rutting problem on asphalt pavements. In this study, a nano-sized-particles-filled polymer composite was developed as an overlay to reflect solar energy and decrease the surface temperature of asphalt pavements. The overlay

He Wang; Jing Zhong; Decheng Feng; Jing Meng; Ning Xie

2012-01-01

402

Low cost pavement marking materials based on plasticized sulfur  

NASA Astrophysics Data System (ADS)

Pavement marking was made more cost effective by reducing the cost of the marking materials. A low cost marking material based on sulfur was developed. Elemental sulfur is a hard, brittle, crystalline material which, on heating, melts to a thin liquid that can be spray applied. If molten elemental sulfur is spray applied to the road as markings, it will on application solidify, crack and adhere poorly to the road. The first ten high speed trucks that ride over the markings will remove them. To make a useful sulfur based pavement marking material it was necessary to chemically modify (plasticize) the sulfur and mix it with fillers and pigments such that it had all of the characteristics desired of a pavement marking material. Yellow and white formulations were developed. For identification they were given the names YS-EIGHT and WS-EIGHT for the yellow and white formulations.

Dale, J. M.

1982-04-01

403

Hot in-place recycling of asphalt pavements. Master's thesis  

SciTech Connect

The purpose of this report is to identify factors to consider in selecting a hot in-place recycling project for asphalt pavements. This report discusses the different types of recycling processes and several selected hot in-place recycling processes that are becoming so popular today. The types of asphalt pavement distress and their causes are discussed to provide a working knowledge of possible applications for this process. Discussions on project selection, design, and construction considerations will also provide an awareness of considerations relative to this type of asphalt-pavement rehabilitation. An understanding of these topics will be helpful when selecting hot in-place recycling. The information that this report is based upon was obtained from various sources. A literature search included technical reports, periodicals, and advertisements. Personal contact was made in the form of interviews with a number of representatives in the industry and on site inspection of Cutler Repaving, Inc. and Remixer Contracting Co., Inc. operations.

Dowdy, M.L.

1987-08-04

404

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

PubMed

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

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

2012-10-12

405

Impact of compressed natural gas fueled buses on street pavements  

SciTech Connect

Capital Metro, the Ausin, Texas transit authority, is currently evaluating a number of CNG fueled buses. As part of the U.S. DOT Region Six University Transportation Centers Program (UTCP), a study was instigated into the scale of incremental pavement consumption associated with the operation of these buses. The study suggests that replacing current vehicles with CNG powered models utilizing aluminum storage tanks would raise average network equivalent single rehabilitation costs across the network of over four percent. Finally, it recommends that full cost study be undertaken with evaluation of the adoption of alternative bus fuels - which includes pavement and environmental impacts.

Yang, D.; Harrison, R.

1995-07-01

406

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

407

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

408

The influence of low-order chord-wise flexibility on the performance of a flapping wing  

Microsoft Academic Search

The aerodynamic role of flexible fight structures in airborne creatures is still poorly understood. The objective of this study is to distill the basic phenomena of flapping with deformable wings for their use in the efficient design of bio-inspired flight vehicles. The target of the study is a two-dimensional wing with rigid components connected by damped torsion springs. This simplified

Jonathan Toomey; Jeff D. Eldredge

2008-01-01

409

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

410

Flexible Scheduling.  

ERIC Educational Resources Information Center

A flexible schedule allows teachers to change group size, group composition, and class length according to the purpose of the lesson. This pamphlet presents various "master" schedules for flexible scheduling: (1) Simple block schedules, (2) back-to-back schedules, (3) interdisciplinary schedules, (4) school-wide block schedules, (5) open-lab…

Davis, Harold S.; Bechard, Joseph E.

411

Assessment of secondary materials for pavement construction: Technical and environmental aspects  

SciTech Connect

Current research at the University of Nottingham to enable the use of secondary materials in road construction covers technical aspects, mechanical properties of waste materials and the environmental implications of their use. Materials studied are minestone, china clay sand, slate waste, pulverized fuel ash and furnace bottom ash. The laboratory program set up for this research and the methodologies suggested for the study of the properties of these materials are presented. The test methods currently used to select pavement aggregates are presented along with current methods for the assessment of the environmental impact of secondary aggregates. The potential of the secondary aggregates is assessed within the current technical and environmental procedures previously presented. Two new methodologies are presented, one for the mechanical examination of secondary aggregates and one for the environmental assessment. The mechanical assessment encompasses conventional characterization and classification tests on both unbound and lightly treated pavement materials, and fundamental tests such as repeated load triaxial tests (RLTT) and repeated load indirect tensile tests (RLITT). Some sample results are presented, suggesting the feasibility and adequacy of this methodology for material discrimination, and evaluation of mechanical properties for design purposes. The environmental assessment indicates how the leaching concentration of contaminants from intensive testing can be used as the first step in assessing the environmental acceptability of a secondary material, and the means of determining a more realistic measure of in situ performance is discussed. The advantages and advancements of the presented methodologies over the basic and inappropriate techniques currently used to assess the suitability of secondary aggregates for use as pavement construction materials are discussed.

Nunes, M.C.M. [Univ. of Nottingham (United Kingdom). Dept. of Civil Engineering]|[National Lab. of Civil Engineering, Lisbon (Portugal); Bridges, M.G.; Dawson, A.R. [Univ. of Nottingham (United Kingdom). Dept. of Civil Engineering

1996-12-31

412

State-of-the-Practice: Rubblization of Airfield Pavements  

Microsoft Academic Search

With the airlines reporting passenger numbers returning to pre - September 11, 2001 levels, demand for more aircraft operations at the nation's airports is continuing to grow. This growth will continue to stress the nation's older concrete airport pavement infrastructure that has already served beyond its design and service limits for which it was constructed. As a result, a major

Mark Buncher; H. Wayne Jones

413

DEVELOPMENT OF A HYDROPHOBIC SUBSTANCE TO MITIGATE PAVEMENT ICE ADHESION  

EPA Science Inventory

The specific problem to which this report is addressed is the development of a hydrophobic substance to mitigate the adhesion of ice to pavement as an alternative to deicing chemicals. The factors involved in evaluating this concept are the following: Economics; safety; environme...

414

Thin-lift recycling of asphalt pavement. SAE Paper 760662  

Microsoft Academic Search

Five basic steps of efficient and economical continuous thin-lift asphalt pavement recycling are listed and the design features of the Cutler Repaver are described. The huge, mobile, self-propelled asphalt paving plant utilizes the five steps with integrated components as follows: softening the old road surface with radiant heat produced by ceramic emitters; loosening a thin layer of old material with

Winderlin

1976-01-01

415

Some experience using noncontact sensors on airport pavements  

NASA Astrophysics Data System (ADS)

The Swedish National Road Administration has been using a laser based system for assessing pavement surface characteristics for over a decade. Typically, important distress data like roughness and rutting are being sampled at speeds up to 25 meters per second. Other parameters include textures and geometric data, such as cross slope and curvature. The Royal Swedish Fortifications Administration has just recently looked into these techniques for airfield pavements. The objectives are similar but not exactly the same as for highway pavements. A promising aspect is using data for building terrain models of the surface so that overlay design procedures can take place in a computerized environment. The objectives are similar but not exactly the same as for highway pavements. A promising aspect is using data for building terrain models of the surface so that overlay design procedures can take place in a computerized environment. Two different ways of treating the data for this purpose was tried. One model uses several parallel continuous longitudinal profiles. The other consists of snap-shot transverse profiles at five meter intervals. The former model yields good assessment of the volumetric needs of either filling or milling operations. The latter is better for identifying features on the surface. The present paper describes some of experiences obtained with the two methods. However, in both cases the most advantageous aspect of using the non-contact devices is the short time needed for collecting the data.

Lenngren, Carl A.

1996-11-01

416

Nitrogen Transformations in Three Types of Permeable Pavement  

EPA Science Inventory

In 2009, USEPA constructed a 0.4-ha (1-ac) parking lot at the Edison Environmental Center in Edison, NJ, that incorporated three different permeable pavement types - permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA). The driving lanes...

417

Impact of compressed natural gas fueled buses on street pavements  

Microsoft Academic Search

Capital Metro, the Ausin, Texas transit authority, is currently evaluating a number of CNG fueled buses. As part of the U.S. DOT Region Six University Transportation Centers Program (UTCP), a study was instigated into the scale of incremental pavement consumption associated with the operation of these buses. The study suggests that replacing current vehicles with CNG powered models utilizing aluminum

D. Yang; R. Harrison

1995-01-01

418

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...

419

Impact of Compressed Natural Gas Fueled Buses on Street Pavements.  

National Technical Information Service (NTIS)

Capital Metro, the Ausin, Texas transit authority, is currently evaluating a number of CNG fueled buses. As part of the U.S. DOT Region Six University Transportation Centers Program (UTCP), a study was instigated into the scale of incremental pavement con...

D. Yang R. Harrison

1995-01-01

420

Guided Wave Approach for Concrete Pavement Thickness Estimation  

Microsoft Academic Search

The basis of a new non-destructive method for concrete pavements is described. The method uses a hybrid approach that combines frequency domain (impact-echo) and time domain (seismic) data. The equipment and data interpretation for the hybrid approach are described. The dynamic response data are interpreted in terms of guided plate wave (Lamb wave) theory, which are shown to follow the

John S. Popovics; Nils Ryden; Alexander Gibson; Michael Haas

2007-01-01

421

Alternative aircraft loading index for pavement structural analysis  

SciTech Connect

The most common practical way to simplify the structural analysis of airfield pavements is the use of equivalent single wheel load models instead of the actual gear of the aircrafts. As the accuracy and reliability of these models strongly affects the design and evaluation of airfield pavements, there is considerable need to investigate both system approaches. The first one, which uses a constant value for the pressure while the radius is variable, is currently under use by the aircraft classification number-pavement classification number method of the International Civil Aviation Organization, but despite this fact it proved to be inadequate to express the aircraft loading in many situations. On the contrary, according to this study, the second model, which has a constant value for the radius while the pressure varies, is more reliable, and it can be an interesting alternative. Thus, based on this model, an aircraft loading index is introduced, which aims to be a simple and reliable factor for expressing the severity of the loading of the aircrafts and a utility for several matters related to the airfield pavement applications.

Loizos, A.; Charonitis, G. [National Technical Univ. of Athens (Greece)

1999-05-01

422

In-pavement wireless sensor network for vehicle classification  

Microsoft Academic Search

Vehicle classication data, especially for trucks, is of considerable use to agencies involved in almost all aspects of transportation and pavement engineering. Current technologies for classication involve expensive installation and calibration procedures. A wireless sensor network (WSN) for vehicle classication based on axle count and spacing was designed, calibrated, tested, and deployed near a weigh station in Sunol, California. The

Ravneet Bajwa; Ram Rajagopal; Pravin Varaiya; Robert Kavaler

2011-01-01

423

Alternative modeling framework for pervious concrete pavement condition analysis  

Microsoft Academic Search

Pervious concrete pavement (PCP) is listed as one of the best stormwater management practices by the Environmental Protection Agency (EPA) due to its capacity to reduce impervious areas, capability to improve water quality, reduce runoff quantity, eliminate the need for detention basins, protect downstream channels, and reduce flooding (save lives and properties). Moreover, it is designated a “Green Asset” since

Amir Golroo; Susan L. Tighe

2011-01-01

424

Reclaimed Asphalt Pavement in Asphalt Mixtures: State of the Practice.  

National Technical Information Service (NTIS)

With increased demand and limited aggregate and binder supply, hot mix asphalt (HMA) producers discovered that reclaimed asphalt pavement (RAP) is a valuable component in HMA. As a result, there has been renewed interest in increasing the amount of RAP us...

A. Copeland

2011-01-01

425

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

426

Flexible workover riser system  

SciTech Connect

A method is described for performing operations in a well selected from a group or cluster of subsea wells which are produced through a production riser means to production facilities on a floating platform. There is provided a flexible workover riser on the platform which extends through a passage on the platform at a location remote from the moon pool for the production riser means. The flexible workover riser is run through said passage and guided into connection with the production tubing in the subsea well. Wireline or other well operations are then conducted through the connected flexible workover riser from the floating platform.

Hall, J.E.

1981-08-04

427

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

Microsoft Academic Search

Preceding results, based on the determination of stable carbon isotope composition (d13C) 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

Jeanne Brulfert; Didier Ravelomanana; Selçuk Güçlü; Manfred Kluge

1996-01-01

428

A Research on the Association of Pavement Surface Damages Using Data Mining  

NASA Astrophysics Data System (ADS)

The association of pavement surface damages used to rely on the judgments of the experts. However, with the accumulation of data in the pavement surface maintenance database and the improvement of Data Mining, there are more and more methods available to explore the association of pavement surface damages. This research adopts Apriori algorithm to conduct association analysis on pavement surface damages. From the experience of experts, it has been believed that the association of road damages is complicated. However, through case studies, it has been found that pavement surface damages are caused among longitudinal cracking, alligator cracking and pen-holes, and they are unidirectional influence. In addition, with the help of association rules, it has been learned that, in pavement surface preventative maintenance, the top priority should be the repair of longitudinal cracking and alligator cracking, which can greatly reduce the occurrence of pen-holes and the risk of state compensations.

Hung, Ching-Tsung; Chang, Jia-Ray; Chen, Jian-Da; Chou, Chien-Cheng; Chen, Shih-Huang

429

Analysis, testing and verification of the behavior of composite pavements under Florida conditions using a heavy vehicle simulator  

NASA Astrophysics Data System (ADS)

Whitetopping (WT) is a rehabilitation method to resurface deteriorated asphalt pavements. While some of these composite pavements have performed very well carrying heavy load, other have shown poor performance with early cracking. With the objective of analyzing the applicability of WT pavements under Florida conditions, a total of nine full-scale WT test sections were constructed and tested using a Heavy Vehicle Simulator (HVS) in the APT facility at the FDOT Material Research Park. The test sections were instrumented to monitor both strain and temperature. A 3-D finite element model was developed to analyze the WT test sections. The model was calibrated and verified using measured FWD deflections and HVS load-induced strains from the test sections. The model was then used to evaluate the potential performance of these test sections under critical temperature-load condition in Florida. Six of the WT pavement test sections had a bonded concrete-asphalt interface by milling, cleaning and spraying with water the asphalt surface. This method produced excellent bonding at the interface, with shear strength of 195 to 220 psi. Three of the test sections were intended to have an unbonded concrete-asphalt interface by applying a debonding agent in the asphalt surface. However, shear strengths between 119 and 135 psi and a careful analysis of the strain and the temperature data indicated a partial bond condition. The computer model was able to satisfactorily model the behavior of the composite pavement by mainly considering material properties from standard laboratory tests and calibrating the spring elements used to model the interface. Reasonable matches between the measured and the calculated strains were achieved when a temperature-dependent AC elastic modulus was included in the analytical model. The expected numbers of repetitions of the 24-kip single axle loads at critical thermal condition were computed for the nine test sections based on maximum tensile stresses and fatigue theory. The results showed that 4" slabs can be used for heavy loads only for low-volume traffic. To withstand the critical load without fear of fatigue failure, 6" slabs and 8" slabs would be needed for joint spacings of 4' and 6', respectively.

Tapia Gutierrez, Patricio Enrique

430

Evolution of desert pavements and the vesicular layer in soils of the Transantarctic Mountains  

Microsoft Academic Search

Compared to mid-latitude deserts, the properties, formation and evolution of desert pavements and the underlying vesicular layer in Antarctica are poorly understood. This study examines the desert pavements and the vesicular layer from seven soil chronosequences in the Transantarctic Mountains that have developed on two contrasting parent materials: sandstone–dolerite and granite–gneiss. The pavement density commonly ranges from 63 to 92%

James G. Bockheim

2010-01-01

431

COMPUTATIONAL MODELING OF PERPETUAL PAVEMENTS USING THE MEPDG VERSION 0.910 SOFTWARE  

Microsoft Academic Search

Because of their long structural life, many US States are exploring the use of perpetual pavements on some of their major highways. By definition, a perpetual pavement (PP) is a thick rut-resistant and fatigue (bottom-up)-resistant pavement structure designed to have a structural life in excess of 50 years, often designed for heavily-trafficked highways. During their service lives, PP structures generally

Lubinda F. Walubita

432

In-Situ Recycling of Deteriorated Concrete Airport Pavements by Rubblization  

Microsoft Academic Search

Rubblization is a method of in-situ recycling of deteriorated concrete pavements. The rubblized layer behaves as a tightly keyed, interlocked, high-density unbound base. At the Federal Aviation Administration's (FAA) National Airport Pavement Test Facility (NAPTF), three rigid airport pavements with 30.5-cm (12-in.) thick concrete slabs on different support systems were rubblized after being trafficked to failure (shattered slab condition) using

N. Garg; D. R. Brill; William J. Hughes

433

Facile chemical synthesis of nanoporous layered ?-MnO2 thin film for high-performance flexible electrochemical capacitors  

NASA Astrophysics Data System (ADS)

Layered ?-MnO2 thin films with a three-dimensional nanostructure are successfully fabricated on stainless steel foil substrates for flexible electrochemical capacitors by a facile and effective chemical bath deposition technology from ethanol and potassium permanganate solution at 15 °C. The as-prepared thin films display nanoporous morphology and a water contact angle of 20°. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses reveal that the thin films are composed of ?-MnO2. Electrochemical data demonstrate that the ?-MnO2 thin film electrodes can deliver a high special capacitance of 447 F/g at 2 mV/s, and provide a good capacitance retention ratio of 87% after 1000 continuous cycles at 10 mV/s in 0.5 M Na2SO4. Compressive and tensile bending tests show that the as-prepared electrodes can steadily work over a wide range of applied curvatures between -2.5 cm-1 (tension) and 2.5 cm-1 (compression). Only a small decrease in special capacitance (0.9% at a curvature of 2.5 cm-1 under compressive strain, or 1.2% at a curvature of -2.5 cm-1 under tensile strain) is observed even after bending for 200 cycles, indicating the excellent mechanical flexibility and electrochemical stability of the ?-MnO2 thin film electrodes.

Hu, Yu; Wang, Jun; Jiang, Xionghua; Zheng, Yanfeng; Chen, Zhenxing

2013-04-01

434

THE OPTIMAL IMPLEMENTATION POLICY OF PAVEMENT INSPECTION WITH DETERIORATION UNCERTAINTY  

NASA Astrophysics Data System (ADS)

This study proposes a methodology to nd the optimal inspection policy for road pavement with uncertain deterioration processes. Since the deterioration progresses are characterized by a lot of uncertainty, the pavement conditions cannot be deterministically evaluated unless the inspection or repair activities are carried out. The road administrators have to make the decisions of whether repair should be implemented based upon the results of inspection. In this paper, the value of the inspection is evaluated by use of real option theory, and the optimal inspection and repair model is formulated to investigate the optimal inspection frequencies and repair policy which may minimize the expected life cycle costs. Finally, the validity of the methodology presented in the paper is investigated by a case study dealing with the expressway in the real world.

Kobayashi, Kiyoshi; Eguchi, Masayuki; Oi, Akira; Aoki, Kazuya; Kaito, Kiyoyuki

435

Assessment of an Impulse GPR Antenna Abilities in Investigation of Transversal Cracks of the Bituminous Pavement  

NASA Astrophysics Data System (ADS)

Ground Penetrating Radar (GPR) technique is commonly used for detection of internal singularities of construction structure. The method is particularly efficient in the case of linear horizontal objects when profile scanning is being performed in the direction perpendicular to object elongation and polarization of the electric field is parallel to the elongation. Then the singular object manifests itself in the echogram as a scattering hyperbola. Similar response is generated by an object having shape close to a vertical half plane with horizontal edge, when the edge acts like the scattering linear object. The use of GPR technique for investigation of transversal cracks in the bituminous pavement would seem to be promising, but numerous paradoxes occur just at the beginning tests. Even well visible cracks of more than ten millimeters thickness doesn't generate noticeable GPR response, while thinner ones sometimes can produce strong response but in the deeper interior of the pavement. Thus arise a more general question: what the GPR technique can tell us about the cracks? Trying to study this problem some laboratory tests were performed to estimate efficiency of signal generation by structures simulating idealized cracks' shapes. Next long-term (several years) visual observation and repeated GPR scanning was performed on the three road sections (each one of several hundred meters length) with heavy traffic, where ongoing cracking process occurs. The preliminary measurements were directed to obtain the proper way of scanning. The main aim of the analysis was to find GPR characteristics of cracks that can be noticed on echograms. It was performed by detailed correlation of the visually observed cracks position with echograms using decimeter precision. These efforts provided a list of diagnostic GPR characteristics of cracks and some provisional scale of their intensity. In several cases the cracks were probed by drillings to recognize structures responsible for signal generation or to explain reasons of lacking signal. The three field cases represent different types of bituminous pavement and different degrees of cracking process progress, what showed first of all a large diversity GPR responses types and existence of specific masking effect related possibly to large-size granulation of the asphalt mixture. These examples show that the strong signals are frequently related to advanced deterioration in lower, older layers and confirm difficulty of cracks detection in a new cover. But on other hand long term observation showed that numerous new cracks appear on the surface in places, where some structural singularities were noticed earlier inside the new construction.

Krysi?ski, L.; Sudyka, J.

2012-04-01

436

Effects of Various Deicing Chemicals on Pavement Concrete Deterioration  

Microsoft Academic Search

The deleterious effects of deicers on concrete pavements and bridges have concerned concrete researchers for several decades. The present study experimentally investigates the effects of different deicers on concrete deterioration. Laboratory simulations of environmental conditions (wet\\/dry and freeze\\/thaw cycling) were conducted on highway concrete samples with various deicer chemicals (NaCl, CaCl 2, MgCl2, calcium magnesium acetate (CMA) of 5 different

HYOMIN LEE; ROBERT D. CODY; ANITA M. CODY; PAUL G. SPRY

437

Leaching of organic contaminants from storage of reclaimed asphalt pavement  

Microsoft Academic Search

Recycling of asphalt has been promoted by rapid increases in both the use and price of petroleum?based bitumen. Semi?volatile organic compounds in leachates from reclaimed asphalt pavement, measured in field samples and in laboratory column test, were analysed through a GC\\/MS screen?test methodology. Sixteen PAH (polyaromatic hydrocarbons) were also analysed in leachates from the column study. The highest concentrations of

Malin Norin

2004-01-01

438

Infiltration Through Desert Pavements, Mojave Desert, CA, USA  

NASA Astrophysics Data System (ADS)

Desert pavements consist of a surface layer of closely packed gravel that overlies thin, gravel-poor vesicular A (Av) soil horizon. Pavements are prominent features in arid and semi-arid environments and can be found on a variety of landforms of significantly diverse ages ranging from Holocene to Tertiary. Well-developed Av profiles form distinct and highly structured prismatic peds. These fine-grained, structured soils can exhibit drastically reduced infiltration rates, rendering some localized areas nearly impermeable and greatly impacting soil development, plant and biota diversity, and groundwater recharge. We sought to study how desert pavement development can impact the hydraulic conductivity characteristics in localized areas (order of 10s of cm). Field sites were chosen at the Mojave Natural Preserve, near Kelso Dunes, CA, USA, which has been the location of considerable prior research by the second author. The sites vary by parent material, clay and silt content, surface age, and variable degree of surface clast cover. Transects were chosen that traversed pavement surfaces of variable development (well developed to poorly developed). Hydraulic conductivity was determined with a tension infiltrometer conducted at different tensions and initial water contents (to better estimate the potential for preferential flow). Sites with dry initial conditions were first analyzed at zero tensions to promote inter-ped flow. After allowing soil peds to hydrate and expand, the tests were run again at a range of soil tensions to promote matrix flow. Differences in saturated conductivities (measured and fitted) were attributed to preferential flow around desiccated peds. Soil texture and structure were measured and described, respectively, allowing for the correlation of conductivity functions to soil surface age and physical characteristics.

Young, M. H.; McDonald, E. V.; Caldwell, T. C.; Benner, S. G.

2003-04-01

439

A novel method of bitumen extraction from asphalt pavement  

SciTech Connect

A new method of extracting bitumen from asphalt pavement mixtures has been developed which does not require chlorinated or aromatic compounds for solvents. The preferred solvent is cyclohexane (although cyclopentane may be used) at high temperatures and pressures. The new method requires equipment that is less costly than the centrifuge method currently used and takes less time than extractions with Bioact but more time than when chlorocompounds are used.

Houser, T.J. (Western Michigan Univ., Kalamazoo (United States))

1990-07-01

440

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

SciTech Connect

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 HMA through a hot mix asphalt plant. This project is to be constructed in two phases, the CRMHMA will be built in the first phase and approximately one year later it will be recycled. This report deals with the first phase in which the objective was to further document the construction, engineering characteristics, and performace of CRMHMA.

Albritton, G.E.; Gatlin, G.R.

1996-08-01

441

Acute Effects of Two Different Warm-Up Protocols on Flexibility and Lower Limb Explosive Performance in Male and Female High Level Athletes  

PubMed Central

This study examined the effects of two different warm-up protocols on lower limb power and flexibility in high level athletes. Twenty international level fencers (10 males and 10 females) performed two warm-up protocols that included 5-min light jogging and either short (15s) or long (45s) static stretching exercises for each of the main leg muscle groups (quadriceps, hamstrings and triceps surae), followed by either 3 sets of 3 (short stretching treatment), or 3 sets of 5 tuck jumps (long stretching treatment), in a randomized crossover design with one week between treatments. Hip joint flexion was measured with a Lafayette goniometer before and after the 5-min warm-up, after stretching and 8 min after the tuck jumps, while counter movement jump (CMJ) performance was evaluated by an Ergojump contact platform, before and after the stretching treatment, as well as immediately after and 8 minutes after the tuck jumps. Three way ANOVA (condition, time, gender) revealed significant time (p < 0.001) and gender (p < 0.001) main effects for hip joint flexion, with no interaction between factors. Flexibility increased by 6. 8 ± 1.1% (p < 0.01) after warm-up and by another 5.8 ± 1.6% (p < 0.01) after stretching, while it remained increased 8 min after the tuck jumps. Women had greater ROM compared with men at all time points (125 ± 8° vs. 94 ± 4° p<0.01 at baseline), but the pattern of change in hip flexibility was not different between genders. CMJ performance was greater in men compared with women at all time points (38.2 ± 1.9 cm vs. 29.8 ± 1.2 cm p < 0.01 at baseline), but the percentage of change CMJ performance was not different between genders. CMJ performance remained unchanged throughout the short stretching protocol, while it decreased by 5.5 ± 0.9% (p < 0.01) after stretching in the long stretching protocol However, 8 min after the tuck jumps, CMJ performance was not different from the baseline value (p = 0.075). In conclusion, lower limb power may be decreased after long periods of stretching, but performance of explosive exercises may reverse this phenomenon. Key points Stretching of the main leg muscle groups for 45 s results in a relatively large decrease (by 5.5%) in subsequent jumping performance Stretching of the main leg muscle groups for only 15 s results in an increase in flexibility similar to that of the longer duration stretching (by 12.6%), with no change in subsequent jumping performance Performance of a PAP exercise such as tuck jumps may reverse the negative effects of long duration stretching on leg muscle power. However, jumping performance is not increased above baseline Speed/power athletes should be advised against using long duration stretching. The number of repetitions of a PAP exercise such as the tuck jumps, should be further examined in order to induce an increase in explosive performance during competition

Tsolakis, Charilaos; Bogdanis, Gregory C.

2012-01-01

442

Flexible nanovectors  

Microsoft Academic Search

In this paper we show that the control of adhesion in highly flexible (a property that could be crucial for smart drug delivery but which is still ignored in the literature) nanovectors can help in smartly targeting and delivering the drug. The existence of and the conditions for activating and controlling a super-adhesive state are addressed. Even if such a

Nicola M. Pugno

2008-01-01

443

PERFORMANCE OF WATERBOUND MACADAM PAVEMENTS CONSTRUCTED LABOUR INTENSIVELY: CASE STUDY  

Microsoft Academic Search

Waterbound Macadam (WM) layers were used extensively during the first half of the previous century and have been reintroduced in the 1980's, focusing on re-engineering labour-intensive construction techniques during the 1990's. In 1994 and 1995 the former Johannesburg Transitional Metropolitan Council (TMC) in consultation with AFRICON and the University of the Witwatersrand constructed two pilot projects in Johannesburg with a

R. J. Moloisane; W. A. van Wyngaard

444

Performance Assessment of Warm Mix Asphalt (WMA) Pavements.  

National Technical Information Service (NTIS)

Warm Mix Asphalt (WMA) is a new technology that was introduced in Europe in 1995. WMA offers several advantages over conventional asphalt concrete mixtures, including: reduced energy consumption, reduced emissions, improved or more uniform binder coating ...

A. S. Al-Rawashdeh J. L. Figueroa S. Sargand W. Edwards

2009-01-01

445

Load Transfer through Aggregate Interlock: Crack Width, Aggregate Type and Performance  

Microsoft Academic Search

It is well known that performance of plain jointed concrete pavements depends on aggregate interlock to transfer load from the one slab to the next. In order to quantify the relative contribution of crack width and the strength of the aggregate to the long- term performance of a plain jointed pavement, experimental sections of road were built using different aggregates

P J Strauss; B D Perrie; L du Plessis; D Rossmann

446

FIELD PERFORMANCE COMPARISON OF HOT POUR SEALANTS AND COLD POUR SEALANTS  

Microsoft Academic Search

Highway agencies have always had the important task of maintaining roads in good condition at a minimum cost. Cracking of pavements has continued to be a challenge for road maintenance, having detrimental effects on a pavement performance and service life, and contributing to high construction and repair costs. It is important to identify high performing materials and repair techniques that

Y. Yildirim; A. Qatan; J. A. Prozzi

447

GPR in Nondestructive Quality Assurance of New Asphalt Pavements  

NASA Astrophysics Data System (ADS)

Mara Nord is an international cooperation project financed by Interreg IVA Nord funding program with partners from Finland, Sweden and Norway. One of the objectives in Mara Nord project has been to research the quality assurance of new asphalt pavement. Ground penetrating radar (GPR) survey is used as an alternative method for coring in quality assurance. There exist numerous advantages for the use of GPR. For example, the fluent measuring arrangements without closing the traffic on the road and the extensive continuous profile that can be constructed from the measuring data. Within the framework of Mara Nord Project field tests were organized in Seinäjoki region in Finland on August 2011. The tests were done by four consulting companies from Finland and Rovaniemi University of Applied Sciences. The aim of these tests was to compare the measured dielectric value profiles and the calculated void content profiles of the equipment. The tested equipment was GSSI manufactured SIR-20 and 1 GHz horn antennas. Void content values were calculated using the model presented by Mr. Roimela (1997). All core samples were taken from the right wheel path. The same reference core samples were used when analyzing the data of each GPR equipment. Some samples were taken right after the pavement work was completed with the rest three weeks after during the test measurements. The tests indicated that GPRs have very good repeatability in measuring dielectric changes on top surface layers of asphalt pavements. Furthermore, different GPRs locate the same detectable longitudinal dielectric changes with high accuracy. Some differences were found in the dielectric value levels, yet reproducibility of the calculated void content values was quite good. The test data was also used to evaluate the reliability of the regression model between the dielectric values measured through GPR and the void content of the pavement determined from reference cores. Test data indicated that accurate regression model could not be validated by using test data because of too wide variation. The variation of void content in core sample results was not always registered by GPR with corresponding variation in dielectric value. There was some moisture present in test conditions and this might have influenced the GPR results. There are some reference data from dry conditions which will be used later on for analyzing the influence of moisture. There was also quite wide variation in void content determined from core samples taken close to each other during field tests. However, wide variation was not seen in core samples taken right after the pavement work. It is possible that traffic load had its effect on the asphalt pavement compaction. The results indicate that when using only one survey line it should be located between wheel paths. Another option is GPR void content measurements should be done right after the pavement work.

Poikajärvi, J.; Peisa, K.; Narbro, A.

2012-04-01

448

Single-crystal SnO2 nanoshuttles: shape-controlled synthesis, perfect flexibility and high-performance field emission  

NASA Astrophysics Data System (ADS)

Vertically aligned single-crystal SnO2 nanoshuttle arrays with uniform morphology and a relatively high aspect ratio were synthesized by a simple hot-wall chemical vapor deposition (CVD) method. It was found that regulating the growth temperature gradient could change the shape of the SnO2 nanostructure from nanoshuttles to nanochisels and nanoneedles, and a self-catalyzing growth process was responsible for tunable morphologies of SnO2 nanostructures. The as-synthesized SnO2 nanoshuttles showed ultrahigh flexibility and strong toughness with a large elastic strain of ~ 6.2, which is much higher than reported for Si and ZnO nanowire as well as most crystalline metallic materials. The field emitter fabricated using SnO2 nanoshuttle arrays has a low turn-on electric field of around 0.6 V µm - 1, and a high field emission current density of above 10 mA cm - 2, which is comparable with the highest emission current density of carbon nanotube and nanowire field emitters.

Li, Junjie; Chen, Meimei; Tian, Shibing; Jin, Aizi; Xia, Xiaoxiang; Gu, Changzhi

2011-12-01

449

Single-crystal SnO(2) nanoshuttles: shape-controlled synthesis, perfect flexibility and high-performance field emission.  

PubMed

Vertically aligned single-crystal SnO(2) nanoshuttle arrays with uniform morphology and a relatively high aspect ratio were synthesized by a simple hot-wall chemical vapor deposition (CVD) method. It was found that regulating the growth temperature gradient could change the shape of the SnO(2) nanostructure from nanoshuttles to nanochisels and nanoneedles, and a self-catalyzing growth process was responsible for tunable morphologies of SnO(2) nanostructures. The as-synthesized SnO(2) nanoshuttles showed ultrahigh flexibility and strong toughness with a large elastic strain of ? 6.2, which is much higher than reported for Si and ZnO nanowire as well as most crystalline metallic materials. The field emitter fabricated using SnO(2) nanoshuttle arrays has a low turn-on electric field of around 0.6 V µm(-1), and a high field emission current density of above 10 mA cm(-2), which is comparable with the highest emission current density of carbon nanotube and nanowire field emitters. PMID:22108293

Li, Junjie; Chen, Meimei; Tian, Shibing; Jin, Aizi; Xia, Xiaoxiang; Gu, Changzhi

2011-11-23

450

Self-organized graphene nanosheets with corrugated, ordered tip structures for high-performance flexible field emission.  

PubMed

Patterned reduced graphene oxide (rGO) films with vertically aligned tip structures are fabricated by a straightforward self-assembly method. The size, uniformity of the patterns, and alignment of the tips are successfully controlled according to the concentration of a GO/octadecylamine (ODA)-dispersed solution. The surface energy difference between the GO/ODA solution and a self-assembled water droplet is a critical parameter for determining the pattern structure. Numerous rGO nanosheets are formed so as to be vertically aligned with respect to the substrate during film fabrication at GO concentrations below 2.0 g/L. These samples provide high field-emission characteristics. The patterned rGO arrays are highly flexible with preservation of the field emission properties, even at large bending angles. This is attributed to the high crystallinity, emitter density, and good chemical stability of the rGO arrays, as well as the strong interactions between the rGO arrays and the substrate. PMID:23335443

Jeong, Hee Jin; Jeong, Hae Deuk; Kim, Ho Young; Jeong, Seung Yol; Han, Joong Tark; Lee, Geon-Woong

2013-01-18

451

Evaluating stepping displacements of pedestrian concrete pavements connected by EPDM rubber and PVC joiners  

Microsoft Academic Search

Pedestrian concrete pavements (sidewalks) are usually made of continuous slabs with simple control joints at a specified interval. Simple control joints such as breaking score lines or saw cuts are created on the pedestrian concrete pavements mainly to relieve stresses resulting from friction and also to avoid displacement\\/unplanned cracking. However, these joints have no load transfer mechanism and therefore the

Y. C. Koay; Y. M. Xie; S. Setunge

2008-01-01

452

Analytical investigation of the effects of dowel misalignment on concrete pavement joint opening behaviour  

Microsoft Academic Search

Experimental and analytical investigations were conducted to evaluate the effects of dowel misalignment on the joint opening behaviour and associated distresses in concrete pavement joints. The experimental investigations focused on pavement specimens with one or two misaligned dowel bars at the joints, and the results included the pull-out force-joint opening responses and the observations of damage (spalling, cracking, etc.). Numerical

Milind Prabhu; Amit Varma; Neeraj Buch

2009-01-01

453

Desert pavement development and landscape stability on the Eastern Libyan Plateau, Egypt  

NASA Astrophysics Data System (ADS)

Desert pavement surfaces of the eastern Libyan Plateau in central Egypt represent a stable landscape preserving Middle and Upper Paleolithic artifacts. Detailed measurements of pavement clasts indicate significant variability in clast size, density, lithology and orientation between pavements, but no spatial relationship among any of these pavement variables over the study area. Pavement characteristics are unrelated to local geomorphic features including slope gradient and aspect, suggesting a desert pavement surface that has developed without significant influence from transporting mechanisms such as overland flow and slope failure. Meridional vertical cracks in surface clasts implicate thermal stresses due to diurnal solar variation as a mechanical weathering process, whereas the presence of a clast-free silty layer within all soil profiles indicates that these are accretionary pavement surfaces that have grown upward over time. The desert pavement in this region has likely developed in situ through mechanical breakdown of surface clasts and desert pedogenesis, indicating long-term stability for this region and minimal taphonomic effects on artifacts > 2 cm in diameter deposited on this surface over the last ca. 100 ka.

Adelsberger, Katherine A.; Smith, Jennifer R.

2009-06-01

454

Asphalt Pavement Aging and Temperature Dependent Properties Using Functionally Graded Viscoelastic Model  

ERIC Educational Resources Information Center

|Asphalt concrete pavements are inherently graded viscoelastic structures. Oxidative aging of asphalt binder and temperature cycling due to climatic conditions being the major cause of non-homogeneity. Current pavement analysis and simulation procedures dwell on the use of layered approach to account for these non-homogeneities. The conventional…

Dave, Eshan V.

2009-01-01

455

Research and Development of GIS Airport Pavement Management System Based on MapX  

Microsoft Academic Search

The load of airport have increased accordingly with the continuous development of air transportation. In order to enhance the maintenance and rehabilitation efficiency of airport pavement, the geographic information system (GIS) airport pavement management system(APMS) based on MapX are being developed in Hunan, one province in middle China. This paper introduce the software and hardware platform, design opinion, main structure

Zhi-Ren Liu; XiangHua Yue

2009-01-01

456

Unified Methodology for Airport Pavement Analysis and Design. Volume 1: State of the ART.  

National Technical Information Service (NTIS)

An assessment of the state of the art of airport pavement analysis and design is presented. The objective is to identify those areas in current airport pavement analysis methodology that need to be substantially improved from the perspective of airport pa...

J. P. Zaniewski

1991-01-01

457

Unified Methodology for Airport Pavement Analysis and Design. Volume 1. State of the Art.  

National Technical Information Service (NTIS)

This report presents an assessment of the state of the art of airport pavement analysis and design. The objective is to identify those areas in current airport pavement analysis methodology that need to be substantially improved from the perspective of ai...

J. P. Zaniewski

1991-01-01

458

Use of Innovative Computer Technology and Optical Texture Properties in the Analysis of Pavement Digital Images  

Microsoft Academic Search

Digital image based automated pavement crack detection and classification technology has seen vast improvements in the recent years. In spite of these developments, although pavement crack lengths and widths can be evaluated using state-of-the-art software with a reasonable accuracy, no reported evidence is found in extending this technology to evaluate crack depths. Hence a preliminary study was carried out to

Saumya Priyadari Amarasiri

2011-01-01

459

Framework for incorporating nondestructive evaluation (NDE) into pavement and bridge management systems  

Microsoft Academic Search

One of the major components of an infrastructure management system is the condition assessment or deterioration modeling. With application to highway pavements and bridges, this paper presents conceptually how nondestructive evaluation (NDE) results can be utilized to provide a quantitative assessment of the infrastructure condition in a format usable for network-level pavement management systems and bridge management systems. NDE techniques

John O. Sobanjo; Kamal S. Tawfiq

1999-01-01

460

Subgrade soil index properties to estimate resilient modulus for pavement design  

Microsoft Academic Search

Mechanistic pavement design procedures based on elastic layer theory require characterization of each material in the pavement structure in terms of elastic moduli. Repeated triaxial load tests on cylindrical disturbed\\/undisturbed samples, yielding a resilient modulus, are frequently used for characterizing subgrade soil. Because of the complexities encountered with the test, in-situ and other laboratory tests would be desirable if a

A. M. Rahim

2005-01-01

461

An Overview of Pervious Concrete Applications in Stormwater Management and Pavement Systems  

Microsoft Academic Search

Recent interest in the use of Portland Cement Pervious Concrete (PCPC) for pavements has been very high, due primarily to the Federal Clean Water Act mandate that government agencies and private entities manage stormwater runoff—both quantity and quality. Such pavements are full depth and are currently being placed primarily in parking lot applications and areas of limited truck traffic. Pervious

V. R. Schaefer; M. T. Suleiman; K. Wang; J. T. Kevern; P. Wiegand

462

Role of conductive spreader layer in reducing surface temperature of HMA pavements  

Microsoft Academic Search

Rutting is a common type of shear failure-related deformation in asphalt (hot mix asphalt, HMA) pavements. It occurs over time as a result of slow, repeated heavy loads from vehicles moving along the wheel path. This problem is most noticeable when the pavement is at a high temperature and its stiffness is the lowest. Previous investigations have concluded that flowing

Sankha Bhowmick; Matthew Medas; Rajib B. Mallick

2012-01-01

463

Automated pavement distress data collection and analysis: a 3-D approach  

Microsoft Academic Search

This paper describes a 3-D automated pavement distress data collection and analysis system based on NRC's Biris sensor technology. The paper introduces the problem to be solved, the selected design criteria, and the adopted solution to monitor the quality of road surfaces. The system geometry for the acquisition of the three-dimensional coordinates of pavement surface distresses is presented. Multiple feature

Liviu Bursanescu; Franqois Blais

1997-01-01

464

Fast detection and symptom analysis of cracks in highway asphalt pavement  

Microsoft Academic Search

A method for real-time fast detection and symptom analysis of cracks in highway asphalt pavement is proposed. At the first step, the fissure characteristic of the acquired and de-noised pavement images is analyzed and then extracted by the method based on gray value comparison between the current pixel and its neighboring pixels, the false cracks are deleted by using the

Hanyu Hong; Xiuhua Zhang; Jiuyang Yu

2009-01-01

465

Electrical resistance tomography for monitoring the infiltration of water into a pavement section  

Microsoft Academic Search

Electrical resistance tomography (ERT) was used to follow the infiltration of water into pavement section at the UC Berkeley Richmond Field Station. A volume of pavement 1m square and 1.29 m deep was sampled by an ERT array consisting of electrodes in 9 drilled holes plus 8 surface electrodes. The data were collected using a computer controlled data acquisition system

M. Buettner; B. Daily; A. Ramirez

1997-01-01

466

Early-life study of the FA409 full-depth asphalt-concrete pavement sections  

SciTech Connect

The Illinois Department of Transportation (IDOT) is currently implementing a mechanistic thickness-design procedure for full-depth asphalt-concrete pavements. This thesis is an early design-life investigation of full-depth asphalt-concrete pavements, constructed on FA409 near Carlyle, Illinois in 1986. Included in the study are: sampling and testing of paving and subgrade materials; extensive non-destructive testing (NDT) using the Falling Weight Deflectometer (FWD); development of techniques for interpreting NDT data; determination of as-built structural characteristics of the various pavement sections; evaluation of subsurface drainage and lime-treated soil behavior; and examination of the validity of the ILLI-PAVE computer model. The simplicity of a full-depth asphalt-concrete pavement allows useful information regarding pavement structure to be determined from FWD surface-deflection data. The ILLI-PAVE model was used in conjunction with statistical methods to quantify, in the form of regression equations or algorithms, the relationship between pavement structure (Tac, Eac, and Eri) and pavement response to FWD loading. Testing of pavement and subgrade material samples as used to validate these algorithms.

Hill, H.J.

1988-01-01

467

Determination of Critical Loading Position on Tied-Arch Bridge Deck Pavement  

Microsoft Academic Search

The universal finite element software of ANSYS was utilized in the mechanical analysis of pavement system on bridge deck. Firstly, the enveloping surface of the interface stress on bridge deck pavement was determined by means of moving loads. Then loads were arranged across the maximum stress influence surface of all the layers according to the criterion. Finally the variation laws

Han Cunjie

2010-01-01

468

How Dutch drinking water production is affected by the use of herbicides on pavements  

Microsoft Academic Search

About forty per cent of drinking water in The Netherlands is produced from surface water. Dutch water companies, that have to rely on this source, are dealing with major water quality problems due to the use of herbicides on pavements. Voluntary measures and bans have had only limited effect on the reduction of emissions of herbicides that runoff from pavements

A. D. Bannink

469

Research on tensile strength characteristics of bridge deck pavement bonding layers  

Microsoft Academic Search

As the development of the traffic in the world, the bridge deck pavement is playing a more and more important role in the whole traffic system. Big span bridge has become more and more especially cement concrete bridge, therefore the bridge deck pavement bonding layers are emphasized as an important part of bridge traffic system, which can mitigate travel impact

Shaopeng Wu; Jun Han

2009-01-01

470

A high speed profiler based slab curvature index for jointed concrete pavement curling and warping analysis  

Microsoft Academic Search

One of the biggest gaps of missing knowledge between accurate structural modeling of concrete pavement slab behavior and real pavement behavior is accounting for slab warping (locked-in curvature and moisture gradient effects) and curling (temperature gradient effects). Curling and warping are curvatures that can be present in a PCC slab that can cause corners and edges, or mid panel, of

Christopher Ronald Byrum

2001-01-01

471

A Field Evaluation of the Use of FBC Flyash for Barnyard Pavement  

Microsoft Academic Search

Pavement of muddy barnyards benefits livestock health by keeping animal feet and udders dryer and cleaner. In spring 1995, fluidized bed combustion (FBC) flyash was installed as a pavement material for barnyards on a farm approximately 40 miles north of Harrisburg, PA. The flyash was transported dry to the site in pneumatic tank trucks and hydrated to approximately 35% using

W. L. Stout; T. L. Nickeson; Paul Cunningham

472

Hydraulic Property Determination of Vesiculated Soil Peds in Desert Pavement Environments  

Microsoft Academic Search

Desert pavements are prominent features in arid and semi-arid environments, and can be found on a variety of landforms of significantly diverse ages ranging from Holocene to Tertiary. Desert pavements consist of a surface layer of closely packed gravel, typically one stone thick, that overlies a silt-rich vesicular A (Av) soil horizon. The vesicular horizon is composed of highly structured,

D. G. Meadows; M. H. Young; T. G. Caldwell; E. V. McDonald

2003-01-01

473

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

Microsoft Academic Search

This work investigates the elastic fields which develop in an overlay bonded to a rigid substrate when the system is subjected to thermally induced stress. A two-dimensional solution of the displacement field is derived for periodic discontinuities distributed in a hot mix asphalt overlay bonded to a rigid pavement, where the length of the pavement before cracking develops is much

H. M. Yin; W. G. Buttlar

2007-01-01

474

Laser-Based 3D Data Acquisition System for the Analysis of Pavement Distress and Roughness.  

National Technical Information Service (NTIS)

In this report we deal with the detection and classification of pavement cracks. Currently, ConnDOT is using Wisecrax which is a commercial product supplied by Roadware. We develop a 3D laser based technique to detect the cracks in a certain pavement sect...

B. Javidi D. Kim S. Kishk

2004-01-01

475

Desert pavement development on the lake shorelines of Lake Eyre (South), South Australia  

Microsoft Academic Search

To the southwest of Lake Eyre (South), South Australia, silcrete boulders exposed by the erosion of the surrounding fine sediments undergo mechanical weathering to form desert pavement. Successive palaeoshorelines of Lake Eyre have exposed an age-related sequence of different stages in the weathering of the boulders. This study investigates desert pavement development in this saline environment. In addition, it attempts

Asma Al-Farraj

2008-01-01

476

Contemporary biogenic formation of clay pavements by eucalypts: further support for the phytotarium concept  

PubMed Central

Background and Aims Clayey (sodosolic) pavements were studied in lateral root catchments of eucalypts where mixed myrtaceous:proteaceous vegetation was colonizing a dune of quartzitic sand blown out from a playa lake during late Pleistocene times. The site at Chillinup in south-west Western Australia provided an opportunity to examine these signature pavements in an unequivocally recent setting, and to assess their effects on competing non-eucalypt vegetation. Methods Pavements were located, and their extents and depths assessed by probing with steel rods, followed by corings and pit excavations using an air spade. Listings of plant species, growth forms and root morphologies were assembled for different vegetation zones in a representative transect across the dune. A deep cutting through the dune provided details on pavement morphology and modifications to the sand deposit bioengineered by eucalypt and heath vegetation. Key Results Clay pavements comprised closely spaced, round-topped columns whose mean diameters and depths varied between eucalypt species. Incipient pavement formation was characterized by clumps of clay deposited around fine root material. Pavements appeared to have been synthesized in situ from locally accessed and imported constituents. Understoreys on superficial pavements of a tree eucalypt were considerably less dense and biodiverse than on the deeper pavements of two mallee species, whilst most profuse vegetation cover was encountered in heath on unmodified (non-pavemented) sand. Certain species were restricted to superficially located pavements, whilst other ‘generalist’ species occurred widely across the dune. Relict pavements formed by earlier generations of eucalypts were present in certain areas of the transect and in soil profiles of the cutting. Some relict pavements colonized by proteaceous shrubs were overprinted with ferricrete. Conclusions Clay pavements formed by eucalypts have pronounced effects on understorey vegetation and may have been instrumental in establishment of the complex mosaics of mallee-woodland and proteaceous heathland observed across semi-arid landscapes of south-west Western Australia. Findings are related to earlier observations on the range of plant-mediated changes in soil profiles discussed in the recently advanced ‘Phytotarium’ concept.

Pate, John S.; Verboom, William H.

2009-01-01

477

Fast detection and symptom analysis of cracks in highway asphalt pavement  

NASA Astrophysics Data System (ADS)

A method for real-time fast detection and symptom analysis of cracks in highway asphalt pavement is proposed. At the first step, the fissure characteristic of the acquired and de-noised pavement images is analyzed and then extracted by the method based on gray value comparison between the current pixel and its neighboring pixels, the false cracks are deleted by using the computed measurement of crack features, thus the true fissures are detected. The most important step is the symptom analysis of the cracks in the pavement image, all the data could be analyzed and be the basis for the agencies to remedy and manage the pavement. Quantities of images are processed and the results show that the proposed method can detect the pavement distress information actually, and has robustness and availability.

Hong, Hanyu; Zhang, Xiuhua; Yu, Jiuyang

2009-10-01

478

Flexible workover riser system  

Microsoft Academic Search

A method is described for performing operations in a well selected from a group or cluster of subsea wells which are produced through a production riser means to production facilities on a floating platform. There is provided a flexible workover riser on the platform which extends through a passage on the platform at a location remote from the moon pool

Hall

1981-01-01

479

Evolving flexible joint morphologies  

Microsoft Academic Search

Transferring virtual robotic designs into physical robots has become possible with the development of 3D printers. Accurately simulating the performance of real robots in a virtual environment requires modeling a variety of conditions, including the physical composition of the robots themselves. In this paper, we investigate how modeling material flexibility through the use of a passive joint affects the resulting

Jared M. Moore; Philip K. McKinley

2012-01-01

480

Flexible CuO Nanosheets/Reduced-Graphene Oxide Composite Paper: Binder-Free Anode for High-Performance Lithium-Ion Batteries.  

PubMed

Flexible free-standing CuO nanosheets (NSs)/reduced graphene oxide (r-GO) hybrid lamellar paper was fabricated through vacuum filtration and hydrothermal reduction processes. A unique three-dimensional nanoporous network was achieved with CuO NSs homogeneously embedded within the r-GO layers. This hybrid lamellar composite paper was examined as a binder-free anode for lithium ion batteries, and demonstrated excellent cyclic retention with the specific capacity of 736.8 mA h g(-1) after 50 cycles. This is much higher than 219.1 mA h g(-1) of the pristine CuO NSs and 60.2 mA h g(-1) of r-GO film at the same current density of 67 mA g(-1). The high capacitance and excellent cycling performance were generated from the integrated nanoporous structure compose of CuO NSs spaced r-GO layers, which offered an efficient electrically conducting channels, favored electrolyte penetration, and buffered to the volume variations during the lithiation and delithiation process. These outstanding electrochemical capabilities of CuO NSs/r-GO paper holds great promise for flexible binder-free anode for lithium ion batteries. PMID:24010720

Liu, Yu; Wang, Wei; Gu, Lin; Wang, Yewu; Ying, Yulong; Mao, Yiyin; Sun, Luwei; Peng, Xinsheng

2013-09-19

481

Influence of pavement macrotexture on PM10 emissions from paved roads: A controlled study  

NASA Astrophysics Data System (ADS)

This paper investigates influence of pavement macrotexture on paved road PM10 emissions. This study was conducted on different paved roadway types (local, collector and minor arterial) in the Las Vegas Valley, Nevada. Pavement macrotexture was measured using the ASTM E 965 sand patch method and the Digital Surface Roughness Meter™ (DSRM™). A controlled constant soil loading with known PM10 fraction was applied to cleaned road surfaces. The Desert Research Institute's (DRI) Mini-PI-SWERL™ (Portable In-Situ Wind ERosion Lab) was used to estimate PM10 mass emissions and cumulative mass emitted from pavement surfaces. PM10 mass emissions using controlled applied soil loadings generally declined with increasing pavement macrotexture at all applied shear levels. The relationships were statistically significant, and indicate that pavement macrotexture may need to be included in future development of revised paved road PM10 emissions factors.A change in the slope of emitted PM10 mass and pavement macrotexture occurred between 0.8 and 0.9 mm mean texture depth (MTD). Anomalies in PM10 mass emissions were observed at MTDs exceeding 1.2 mm. Two-way frequency distributions of pavement surface features obtained from DSRM measurements were analyzed to explain the observed anomalies. Results showed that pavement surface feature size distributions may influence on PM10 emissions from paved roads at similar MTDs.PM10 mass emissions were found to linearly depend on adjusted mode size of the pavement surface aggregate. A sharp decrease in friction velocities, computed from wind erosion theory, at MTDs above 0.9 mm matched an observed sharp decrease in PM10 emissions rates at MTDs above 0.9 mm, indicating that classical wind erosion theory could be adapted for non-erodible pavement surfaces and linearly relate PM10 emissions rates to applied shear stress at an aerodynamic roughness height of 0.075 mm.

China, Swarup; James, David E.

2012-12-01

482

Strain gage installation and survivability on geosynthetics used in flexible pavements  

Microsoft Academic Search

The use of foil type strain gages on geosynthetics is poorly documented. In addition, very few individuals are versed in proper installation techniques or calibration methods. Due to the limited number of knowledgeable technicians there is no information regarding the susceptibility of theses gages to errors in installation by inexperienced installers. Also lacking in the documentation related to the use

Jeremy A. Brooks

2009-01-01

483

Strain gage installation and survivability on geosynthetics used in flexible pavements  

NASA Astrophysics Data System (ADS)

The use of foil type strain gages on geosynthetics is poorly documented. In addition, very few individuals are versed in proper installation techniques or calibration methods. Due to the limited number of knowledgeable technicians there is no information regarding the susceptibility of theses gages to errors in installation by inexperienced installers. Also lacking in the documentation related to the use of foil type strain gages on geosynthetics is the survivability of the gages in field conditions. This research documented procedures for installation, calibration, and survivability used by the project team to instruments a full scale field installation in Marked Tree, AR. This research also addressed sensitivity to installation errors on both geotextile and geogrid. To document the process of gage installation an experienced technician, Mr. Joe Ables, formerly of the UASCE Waterways Experiment Station, was consulted. His techniques were combined with those discovered in related literature and those developed by the research team to develop processes that were adaptable to multiple gage geometries and parent geosynthetics. These processes were described and documented in a step by step manner with accompanying photographs, which should allow virtually anyone with basic electronics knowledge to install these gages properly. Calibration of the various geosynthetic / strain gage combinations was completed using wide width tensile testing on multiple samples of each material. The tensile testing process was documented and analyzed using digital photography to analyze strain on the strain gage itself. Calibration factors for each geosynthtics used in the full scale field testing were developed. In addition, the process was thoroughly documented to allow future researchers to calibrate additional strain gage and geosynthetic combinations. The sensitivity of the strain gages to installation errors was analyzed using wide width tensile testing and digital photography to determine the variability of the data collected from gages with noticeable installation errors as compared to properly installed gages. Induced errors varied based on the parent geosynthetics material, but included excessive and minimal waterproofing, gage rotation, gage shift, excessive and minimal adhesive, and excessive and minimal adhesive impregnation loads. The results of this work indicated that minor errors in geotextile gage installation that are noticeable and preventable by the experienced installer have no statistical significance on the data recorded during the life span of geotextile gages; however the lifespan of the gage may be noticeably shortened by such errors. Geogrid gage installation errors were found to cause statistically significant changes in the data recorded from improper installations. The issue of gage survivability was analyzed using small scale test sections instrumented and loaded similarly to field conditions anticipated during traditional roadway construction. Five methods of protection were tested for both geotextile and geogrid including a sand blanket, inversion, semi-hemispherical PCV sections, neoprene mats, and geosynthetic wick drain. Based on this testing neoprene mats were selected to protect geotextile installed gages, and wick drains were selected to protect geogrid installed gages. These methods resulted in survivability rates of 73% and 100% in the full scale installation respectively. This research and documentation may be used to train technicians to install and calibrate geosynthetic mounted foil type strain gages. In addition, technicians should be able to install gages in the field with a high probability of gage survivability using the protection methods recommended.

Brooks, Jeremy A.

484

Guayule Plant: A Renewable, Domestic Source of Binder Materials for Flexible Pavement Mixtures.  

National Technical Information Service (NTIS)

The guayule (pronounced 'why-YOU-lee') plant grows in arid and semi-arid regions (e.g. the southwestern U.S.) and is a source of natural rubber. It was cultivated and processed during the World War II rubber shortage and is currently being processed prima...

D. N. Richardson S. M. Lusher

2013-01-01

485

A Study of CRCP Performance: New Construction vs. Overlay.  

National Technical Information Service (NTIS)

This report documents the performance of several continuously reinforced concrete pavements (CRCP) in Texas. Specifically, it involves a comparison of the performances of CRCP overlays and new CRCP construction for three projects: I35-2(45)175, located in...

J. I. Daniel W. R. Hudson B. F. McCullough

1978-01-01

486

Human resource bundles and manufacturing performance: Organizational logic and flexible production systems in the world auto industry  

Microsoft Academic Search

Using a unique international data set from a 1989-90 survey of 62 automotive assembly plants, the author tests two hypotheses: that innovative HR practices affect performance not individually but as interrelated elements in an internally consistent HR \\

John MacDuffie

1995-01-01

487

Re-Examining the Performance of MRP and Kanban Material Control Strategies for Multi-Product Flexible Manufacturing Systems  

Microsoft Academic Search

Material control schemes can be classified as push, pull, or hybrid strategies. This article compares the performance of MRP (push) and kanban (pull) for a multi-stage, multi-product manufacturing system. Using simulation experiments we analyze system performance under different product mixes and observe that in certain environments with advance demand information kanban-based pull strategies can lead to significant inefficiencies. In these

Ananth Krishnamurthy; Rajan Suri; Mary Vernon

2004-01-01

488

A performance evaluation method of preformed joint sealant: Slip-down failure  

Microsoft Academic Search

Various preformed joint sealants (PJS) can be used for joint concrete pavement (JCP) to prevent the JCP from distresses such as pumping and faulting. Even though PJS have an important role in concrete pavement structures, most of the test methods that assess PJS focus on evaluating their basic mechanical and chemical properties rather than performance-related properties. In this study, a

Taeyoung Yun; Oleg Lee; Seung Woo Lee; In Tai Kim; Yoon-Ho Cho

2011-01-01

489

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

SciTech Connect

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 petroleum asphalts were first aged by a thin-film accelerated-aging test, which simulates long service life of asphalt in pavement. The aged asphalts were mixed (recycled) with Green River Formation shale oil distillation residua to restore the original viscosities. Separately, for comparison, a commercial recycling agent was used to recycle the aged asphalts under the same circumstances. The recycled asphalts were reaged and the properties of both binder and asphalt-aggregate mixtures studied. Originally, the same study was intended for an eastern shale residua. However, the eastern shale oil distillation residua with the required flash point specification also had the properties of a viscosity builder; therefore, it was studied as such with asphalts that do not achieve sufficient viscosity during processing to serve as usable binders. Results show that Green River Formation shale oil residuum can be used to restore the original asphalt properties with favorable rheological properties, the shale oil residuum has a beneficial effect on resistance to moisture damage, the low-temperature properties of the shale oil residuum recycled asphalts are not adversely affected, and the low-temperature properties of the shale oil residuum recycled asphalts are dependent upon the chemistry of the mixture. The eastern shale oil residua was blended with soft petroleum asphalts. Results show the products have higher viscosities than the starting materials, the rheological properties of the soft asphalt-eastern shale oil residue blends are acceptable, and the eastern shale oil residue has dispersant properties despite its high viscosity. 11 refs., 3 figs., 9 tabs.

Harnsberger, P.M.; Robertson, R.E.

1990-03-01

490

Flexible nanovectors  

NASA Astrophysics Data System (ADS)

In this paper we show that the control of adhesion in highly flexible (a property that could be crucial for smart drug delivery but which is still ignored in the literature) nanovectors can help in smartly targeting and delivering the drug. The existence of and the conditions for activating and controlling a super-adhesive state are addressed. Even if such a state has never been observed in nanovectors, our calculations, as well as observations in spiders and geckos, suggest its existence and feasible control. Control of the competition between the drag and the adhesive force is exploited to improve the targeting ability and a hierarchical model is applied to describe a real vasculature. The high flexibility of the nanovector is used to smartly deliver the drug only during adhesion by nanopumping or, as a limiting case, by the new concept of 'adhesion induced nanovector implosion'; a liquid drop analogy is utilized for the calculations. Fast (pumping) and slow (diffusion) drug deliveries can thus be separately controlled by controlling the size and shape of the nanovector. Multiple stage nanovectors are also briefly discussed, mimicking aerospace vector strategies.

Pugno, Nicola M.

2008-11-01

491

Solar-reflective coating as a cooling overlay for asphalt pavement  

NASA Astrophysics Data System (ADS)

Rutting is one of the most serious problems on asphalt pavements. Decrease the surface temperature of the asphalt pavement is an effective method to solve the rutting problem on asphalt pavements. In this study, nano sized particles filled polymer composite was developed as an overlay to reflect the solar energy and decrease the surface temperature of asphalt pavements. The overlay was composed of acrylic or epoxy resin filled with nano TiO2 or nano TiNO2. The solar reflection of the nano particle filled polymers was tested and the results showed that solar reflection effectiveness of the epoxy/TiO2 composite reached the highest value. The results of outdoor temperature test indicate that the solar-reflective overlay could decrease the surface temperature of asphalt pavements about 10 °C when the pavement temperature is about 60 °C. Pavement skid resistance was also tested, which expressed by micro/macrotexture depth and the results of which showed that both matrix was qualified after coated with aggregates on the surface.

Wang, He; Xu, Geng; Feng, Decheng; Zhong, Jing; Xie, Ning

2011-11-01

492

Decision model in the laser scanning system for pavement crack detection  

NASA Astrophysics Data System (ADS)

Pavement crack detection plays an important role in the pavement maintaining and management. Recently, the laser scanning technique for pavement crack detection becomes more and more popular due to its ability of discriminating dark areas, which are not caused by pavement distress such as tire marks, oil spills, and shadows. However, this technique still bears some errors for pavement crack recognition errors, thus in the present work, the factors contributed to these errors in laser scanning system are first analyzed, and then a decision model for the laser scanning pavement crack detection system based on the hypothesis test is proposed. Experimental analyses and results show that this model not only allows us to build the relationship between the contribution factors and crack detection accuracy and to provide the criteria to compare the detection accuracy for the different roads, but also can be used to judge whether the crack exists with a reasonable number of deformed light stripes. Therefore, the proposed decision model can provide guidance on the pavement crack detection and has a practical value.

Sun, Xiaoming; Huang, Jianping; Liu, Wanyu

2011-12-01

493

Portable Profiler for Pavement Profile Measurements.  

National Technical Information Service (NTIS)

This interim report provides a summary of work performed on Texas Department of Transportation (TxDOT) Research Project 0-6004 during the first year of the project. The project was initiated to develop a single path, easy to use, portable profiler. The de...

E. Fernando R. S. Walker

2009-01-01

494

Air Purification Pavement Surface Coating by Atmospheric Pressure Cold Plasma  

NASA Astrophysics Data System (ADS)

This study develops an atmospheric pressure cold plasma (APCP) reactor to produce activated radicals from precursor molecules, and to immobilize nano titanium dioxide (TiO2) powder to substrate pavement materials. TiO2 has photocatalytic properties and under UV light can be used to oxidize and remove volatile organic compounds (VOCs) and nitrogen oxides (NOx) from the atmosphere. Although TiO2 treated paving materials have great potential to improve air quality, current techniques to adhere TiO2 to substrate materials are either not durable or reduce direct contact of TiO2 with UV light, reducing the photocatalytic effect. To solve this technical difficulty, this study introduces APCP techniques to transportation engineering to coat TiO2 to pavement. Preliminary results are promising and show that TiO2 can be incorporated successfully into an APCP environment and can be immobilized at the surface of the asphalt substrate. The TiO2 coated material with APCP shows the ability to reduce nitrogen oxides when exposed to UV light in an environmental chamber. The plasma reactor utilizes high voltage streamers as the plasma source.

Westergreen, Joe; Pedrow, Patrick; Shen, Shihui; Jobson, Bertram

2011-11-01

495

Overlays for plain jointed concrete pavements  

NASA Astrophysics Data System (ADS)

This report describes the construction and performance of 4 concrete and 16 asphalt overlay test sections after nine years of traffic. The test sections were placed on I-85 which carries a substantial number of heavy trucks to determine what treatments and overlay type and thickness would give acceptable performance. The concrete overlay sections were placed in 1975 and consisted of 3 inch, 4 1/2 inch, and 6 inch CRC and 6 inch jointed PCC with 15 ft. and 30 ft. joint spacing. The asphalt sections were placed in 1976 with the variables being overlay thickness of 2 inches, 4 inches, and 6 inches and the placement of two geotextiles and strips of a waterproofing membrane for each overlay thickness. An Arkansas base test section was also included in the experiment.

Gulden, W.; Brown, D.

1984-09-01

496

Evaluation of low temperature cracking in asphalt pavement mixes. Technical report  

SciTech Connect

This report examines the feasibility of using the thermal stress restrained specimen test to evaluate low temperature cracking in asphalt pavement mixes. Data were collected from laboratory and field evaluations. Various mixing, aging, and compaction methods were used to prepare test samples with materials obtained from two WYDOT highway projects. Field data were obtained from two recently built test sections to compare with laboratory test results. Pavement condition surveys quantified low temperature cracking of both test sections after one winter. Temperature data for these projects sites were also collected. Pavement condition and temperature data were compared to results from the thermal stress restrained specimen test.

Ksaibati, K.; Erickson, R.

1998-10-01

497

Pavement-management system for concrete roadways in Virginia. Phase 1. Condition ratings. Final report  

SciTech Connect

The report traces the development of a rating system for evaluating the service condition of Virginia's portland-cement concrete pavements. The service condition is assessed in terms of distress roughness, i.e., that portion of a pavement's poor-ride characteristics directly attributable to the occurrence of certain key distress types. Field surveys of the occurrence of these distresses provide the necessary data for estimating distress roughness through the use of prediction equations that have been established from the standard statistical analysis of pavement-section distress data and roughness measurements. Distress measurements and their corresponding ratings and a condition survey rating procedure are appended.

Long, R.R.

1988-04-01

498

Management of flexible manufacturing: An international comparison  

Microsoft Academic Search

The purpose of this paper is (1) to examine the current status of flexible manufacturing in the United States and Sweden, (2) to survey the historical reasons for existing differences, and (3) to explore the impact of flexibility on various aspects of performance, particularly international competitiveness. The most recent data on the use of certain hardware associated with flexibility, such

B Carlsson

1992-01-01

499

Quantifying machine flexibility  

Microsoft Academic Search

There are several studies aiming to quantify several aspects of flexibility in manufacturing systems like routing flexibility, product mix flexibility, volume flexibility, etc. However, there is still a need to develop more generic measures that can be used to quantify flexibility of systems in order to enable decision-makers to reach better decisions in selecting between different system configurations. In this

Adil Baykaso?lu

2009-01-01

500

Pavement Marking Warranty Specifications. A Synthesis of Highway Practice. NCHRP Synthesis 408.  

National Technical Information Service (NTIS)

This synthesis study updates information on the use of pavement marking warranties by U.S. state departments of transportation (DOTs) and Canadian provincial/territorial transportation agencies. It also reviews road construction warranty experience in Eur...

M. J. Markow

2010-01-01