Sample records for flexible pavement performance

  1. Aggregate and disaggregate statistical evaluation of the performance-based effectiveness of long-term pavement performance specific pavement study-5 (LTPP SPS-5) flexible pavement rehabilitation treatments

    Microsoft Academic Search

    Anwaar Ahmed; Samuel Labi; Zongzhi Li; Todd Shields

    2010-01-01

    Engineers continually seek effective techniques for preserving highway infrastructure. Using data from the specific pavement study#5 of the long-term pavement performance (LTPP) programme's western region, this article evaluated the performance of eight flexible pavement rehabilitation treatments. Aggregate and disaggregate post-treatment performance models were developed for each treatment. Effectiveness was measured in the short term (roughness reduction) and long term (estimated

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

    E-print Network

    Deshpande, Vighnesh Prakash

    2009-05-15

    that require the reliability (performance) of pavements, before and after the rehabilitation actions. The response surface methodology in conjunction with Monte Carlo simulation is used to evaluate pavement fragilities. To provide more flexibility...

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

    E-print Network

    Deshpande, Vighnesh Prakash

    2009-05-15

    A performance model and a reliability-based optimization model for flexible pavements that accounts for the effects of rehabilitation actions are developed. The developed performance model can be effectively implemented in all the applications...

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

    Microsoft Academic Search

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

    2011-01-01

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

  5. Analysis of Flexible Pavements Reinforced with Geogrids

    Microsoft Academic Search

    Hema Siriwardane; Raj Gondle; Bora Kutuk

    2010-01-01

    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

  6. Geotextiles in Flexible Pavement Construction

    ERIC Educational Resources Information Center

    Alungbe, Gabriel D.

    2004-01-01

    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…

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

    E-print Network

    Jamy, Ahmad Najeeb

    1991-01-01

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

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

    E-print Network

    Jamy, Ahmad Najeeb

    1991-01-01

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

  9. Adaptive prediction of pavement performance 

    E-print Network

    Zulyaminayn, Mohammed

    2002-01-01

    A Visual Basic 6.0[TM] computer program for adjusting family performance curves in making reasonable predictions of individual pavement section performance has been developed under this study. The methodology formulated ...

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

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

    E-print Network

    . Developing concrete mix design(s) that meets the performance requirements for the intended pavement; 4 Special Provision for Ternary Concrete Mix Designs for Composite Pavement. EQUIPMENT Equipment shall of no more than 50% of the total cementitious material in any mix design. Composite pavement refers

  12. Field evaluation and analysis of flexible pavement structural responses under dynamic loads

    Microsoft Academic Search

    Alireza Bayat; Mark Knight

    2012-01-01

    This study investigates the structural responses of flexible pavements at the Center for Pavement and Transportation Technology (CPATT) test track located at Waterloo, Ontario, Canada. A comprehensive field testing program was performed to examine flexible pavement responses to a variety of loading conditions. Tests were completed using six tire types: 11R22.5, 275\\/80R22.5, 295\\/75R22.5, and 285\\/70R22.5 dual tires, and 455\\/55R22.5 and

  13. of Concrete Pavements Joint PerformanCe

    E-print Network

    practitioners under- stand how to optimize concrete pavement joint perfor- mance through the identificationof Concrete Pavements Joint PerformanCe interim Guide for optimum JUNE 2012 #12;#12;Interim Guide for Optimum Joint Performance of Concrete Pavements i Technical Report Documentation Page 1. Report No. 2

  14. Significance of bearing capacity of clayey subgrade in flexible pavement design

    Microsoft Academic Search

    C. N. V. Satyanarayana Reddy; N. V. Rama Moorthy

    2005-01-01

    Clays as subgrades pose serious problems to flexible pavements built over them as they retain moisture for a longer period and possess low strength. Excessive settlements along the wheel tracks on pavement surface and bearing capacity failures in the subgrade soil are often observed in the flexible pavements constructed over such subgrades. So, the present status of flexible pavements in

  15. Study on Flexible Pavement Failures in Soft Soil Tropical Regions

    NASA Astrophysics Data System (ADS)

    Jayakumar, M.; Chee Soon, Lee

    2015-04-01

    Road network system experienced rapid upgrowth since ages ago and it started developing in Malaysia during the colonization of British due to its significant impacts in transportation field. Flexible pavement, the major road network in Malaysia, has been deteriorating by various types of distresses which cause descending serviceability of the pavement structure. This paper discusses the pavement condition assessment carried out in Sarawak and Sabah, Malaysia to have design solutions for flexible pavement failures. Field tests were conducted to examine the subgrade strength of existing roads in Sarawak at various failure locations, to assess the impact of subgrade strength on pavement failures. Research outcomes from field condition assessment and subgrade testing showed that the critical causes of pavement failures are inadequate design and maintenance of drainage system and shoulder cross fall, along with inadequate pavement thickness provided by may be assuming the conservative value of soil strength at optimum moisture content, whereas the exiting and expected subgrade strengths at equilibrium moisture content are far below. Our further research shows that stabilized existing recycled asphalt and base materials to use as a sub-base along with bitumen stabilized open graded base in the pavement composition may be a viable solution for pavement failures.

  16. Simulation of Flexible Pavement Design in Kansas

    Microsoft Academic Search

    Mustaque Hossain; Stefan A. Romanoschi; Andrew J. Gisi

    The Kansas Department of Transportation (KDOT) is currently adopting the Mechanistic-Empirical Pavement Design Guide (MEPDG) to replace the 1993 American Association of State Highway and Transportation Officials (AASHTO) design method. It would be valuable for the designer to know whether the MEPDG design simulation analysis would predict the actual distresses observed in Kansas. Thus, five newly built Superpave pavements, designed

  17. Layer equivalency factors and deformation characteristics of flexible pavements 

    E-print Network

    Hung, Jung-Tsann

    1981-01-01

    of Texas Triaxial Test Texas Classification of Subgrade and Flexible Hase Materials Vlasov Model Subjected to a Distributed Load . Vlasov Model Subjected to a Rigid Circular Plate . Testing Layout of Dynaflect, Pressuremeter and Sampling... method for obta1ning layer equ1valency factors. There is also a crit1cal need to update the pavement modeling of the Flex1ble Pavement System (FPS) and to convert it to a layered elastic modeling for 2 reasons: ( I) elastic moduli can be measured...

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

    E-print Network

    Salehi Ashtiani, Reza

    2010-10-12

    The aggregate base layer is a vital part of the flexible pavement system. Unlike rigid pavements, the base layer provides a substantial contribution to the load bearing capacity in flexible pavements, and this contribution is complex: stress...

  19. Pavement performance modelling with an auto-regression approach

    Microsoft Academic Search

    Z. Luo

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Kowalski, Karol J.

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

  1. Truck fleet model for design and assessment of flexible pavements

    NASA Astrophysics Data System (ADS)

    Belay, Abraham; OBrien, Eugene; Kroese, Dirk

    2008-04-01

    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.

  2. 1 INTRODUCTION A typical flexible pavement system includes four

    E-print Network

    Zornberg, Jorge G.

    in pavement design to address the functions of separation, filtration, lateral drainage, sealing to perform a filtration function by restricting the movement of soil particles from the subgrade while allowing water to move to the coarser adjacent base material. In-plane drainage function of a geosynthetic

  3. Re-Evaluation of the AASHTO-Flexible Pavement Design Equation with Neural Network Modeling

    PubMed Central

    Ti?demir, Mesut

    2014-01-01

    Here we establish that equivalent single-axle loads values can be estimated using artificial neural networks without the complex design equality of American Association of State Highway and Transportation Officials (AASHTO). More importantly, we find that the neural network model gives the coefficients to be able to obtain the actual load values using the AASHTO design values. Thus, those design traffic values that might result in deterioration can be better calculated using the neural networks model than with the AASHTO design equation. The artificial neural network method is used for this purpose. The existing AASHTO flexible pavement design equation does not currently predict the pavement performance of the strategic highway research program (Long Term Pavement Performance studies) test sections very accurately, and typically over-estimates the number of equivalent single axle loads needed to cause a measured loss of the present serviceability index. Here we aimed to demonstrate that the proposed neural network model can more accurately represent the loads values data, compared against the performance of the AASHTO formula. It is concluded that the neural network may be an appropriate tool for the development of databased-nonparametric models of pavement performance. PMID:25397962

  4. A numerical model for flexible pavements rut depth evolution with time

    NASA Astrophysics Data System (ADS)

    Allou, Fatima; Chazallon, Cyrille; Hornych, Pierre

    2007-01-01

    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

  5. Performance of pavements designed with low-cost materials

    NASA Astrophysics Data System (ADS)

    Grau, R. W.; Yrjanson, W. A.; Packard, R. G.; Barksdale, R. D.; Potts, C. F.; Ruth, B. E.; Smith, L. L.; Huddleston, I. J.; Vinson, T. S.; Hicks, R. G.

    1980-04-01

    The following areas are discussed. Utilization of marginal aggregate materials for secondary road surface layers; econocrete pavements; current practices; construction and performance of sand-asphalt bases and performance of sand-asphalt and limerock pavements in Florida. Cement stabilization of degrading aggregates use of crushed stone screenings in highway construction (abridgement); and sulfur-asphalt pavement technology are also reviewed.

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

    SciTech Connect

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

    1999-02-01

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

  7. Performance of pavements designed with low-cost materials

    Microsoft Academic Search

    R. W. Grau; W. A. Yrjanson; R. G. Packard; R. D. Barksdale; C. F. Potts; B. E. Ruth; L. L. Smith; I. J. Huddleston; T. S. Vinson; R. G. Hicks

    1980-01-01

    The following areas are discussed. Utilization of marginal aggregate materials for secondary road surface layers; econocrete pavements; current practices; construction and performance of sand-asphalt bases and performance of sand-asphalt and limerock pavements in Florida. Cement stabilization of degrading aggregates use of crushed stone screenings in highway construction (abridgement); and sulfur-asphalt pavement technology are also reviewed. Bibtex entry for this abstract

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

    NASA Astrophysics Data System (ADS)

    Ahsanuzzaman, Md

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

  9. Fuzzy optimization BP neural network model for pavement performance assessment

    Microsoft Academic Search

    Yan Liu; Min Sun

    2007-01-01

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

  10. Monitoring the performance of geosynthetic materials within pavement systems using MEMS

    NASA Astrophysics Data System (ADS)

    Attoh-Okine, Nii O.; Ayenu-Prah, Albert Y.; Mensah, Stephen A.

    2005-05-01

    Geosynthetic materials have found useful applications when unbound aggregates have been placed on cohesive soil with very weak subgrade. They have also been successfully used in retarding reflective cracking in both flexible and composite pavements. There are many applications of geosynthetics in pavement engineering yet there is considerable lack of understanding in the behavior of the material. Geosynthetic materials exhibit very peculiar properties in the area of tensile strength and reinforcement. MEMS are miniature sensing or actuating devices that can interact with other environments (provided no adverse reaction occurs) to either obtain information or alter it. With remote query capability, it appears such devices can be embedded in pavement systems as testing and monitoring tools. The aim of this paper is to propose both field and laboratory methods for monitoring geotextile performance using MEMS.

  11. Influence of Different Rheological Models on Predicted Pavement Responses in Flexible Pavements

    Microsoft Academic Search

    Roger N Nilsson; Piet C. Hopman; Ulf Isacsson

    2002-01-01

    Conventional response models are based on linear elastic theory and stationary loading. Such models are in principle considered inadequate for predicting actual pavement responses. Since bitumnous mixes exhibits viscoelastic properties and the wheel loads are moving, several rheological models have been proposed for describing mechanical properties of bituminous mixes. However, many of these models are capable of representing a material

  12. TYRE-PAVEMENT INTERFACE CONTACT STRESSES ON FLEXIBLE PAVEMENTS - QUO VADIS?

    Microsoft Academic Search

    M. De Beer; C. Fisher; L. Kannemeyer

    Worldwide, road pavement networks are constantly under pressure of an ever increasing demand from economic and other market forces. As a result, road infrastructure needs constant protection and it is therefore necessary to understand the ever-changing operating conditions such as the impact of heavy vehicles (HVs). Since the previous CAPSA 1999 conference further progress has been made with the application

  13. Improving Rutting Resistance of Pavement Structures Using Geosynthetics: An Overview

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

  15. Comparison of measured vs. predicted performance of jointed plain concrete pavements using the Mechanistic–Empirical Pavement Design Guideline

    Microsoft Academic Search

    J. M. Vandenbossche; F. Mu; T. R. Burnham

    2011-01-01

    This research evaluates the ability of the Mechanistic–Empirical Pavement Design Guide (MEPDG) to accurately predict the performance of jointed plain concrete pavements (JPCPs). This is accomplished by comparing predicted performances with observed performances for the in-service mainline test cells at Mn\\/ROAD. These comparisons indicate that MEPDG performance predictions for JPCP are most accurate when the default (constant) built-in equivalent temperature

  16. Identification of asphalt binder properties that affect cracking performance of hot mixed asphalt concrete pavements 

    E-print Network

    Hastings, Charles Patrick

    1997-01-01

    The overall objective of this study was to identify binder properties that affect cracking performance of hot mixed asphalt concrete (HMAC) pavements. In the late 1980s, test pavements were constructed in Texarkana and Sherman, Texas. In 1995...

  17. Porous Pavement in Cold Climates Part: Performance and Cost

    E-print Network

    ) diameter perforated subdrains with 2" cover Optional-Liner for land uses where infiltration is undesirable 90 80 70 60 50 40 30 20 10 0 %RemovalEfficiency Porous Asphalt Pervious Concrete Retention Pond ` #12;17 Hydrrologic Performance of Porous Pavements Pervious Concrete (HSG-B)Porous Asphalt (HSG-C) #12;0 10 20 30 40

  18. Monitoring the performance of geosynthetic materials within pavement systems using MEMS

    Microsoft Academic Search

    Nii O. Attoh-Okine; Albert Y. Ayenu-Prah; Stephen A. Mensah

    2005-01-01

    Geosynthetic materials have found useful applications when unbound aggregates have been placed on cohesive soil with very weak subgrade. They have also been successfully used in retarding reflective cracking in both flexible and composite pavements. There are many applications of geosynthetics in pavement engineering yet there is considerable lack of understanding in the behavior of the material. Geosynthetic materials exhibit

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

    E-print Network

    Acharya, Bhagaban

    2011-12-31

    ABSTRACT The reprocessed old hot mix asphalt (HMA) concrete also called "Recycled Asphalt Pavement (RAP)", if used to build new roads or to maintain existing roads, would have several benefits, such as preservation of natural resources for future...

  20. Flexible sigmoidoscopy performed by nurses.

    PubMed

    Goodfellow, P B

    2006-06-01

    Flexible sigmoidoscopy by nurses has rapidly become a widely accepted technique for distal colonic investigation. This review explores the issues of training and application of nurse performed flexible sigmoidoscopy, including the limitations, complications and cost issues. PMID:16586240

  1. Safety Performance of Experimental Pavement Types in California Using Before-and-After Comparisons

    Microsoft Academic Search

    Soonmi Oh; David R Ragland; Ching-Yao Chan

    2010-01-01

    This study focused on safety performance of new pavement surface types. Open graded or coarse-textured roadway surfaces are advisable for high-speed, wet-weather traffic conditions. They provide drainage relief at the tire-pavement interface, reduce the steepness of the speed gradient, decrease the likelihood of hydroplaning, minimize splash and spray, reduce the glare from wet pavements, and improve high-speed skid resistance. Before-and-after

  2. An investigation into the predictive performance of pavement marking retroreflectivity measured under various conditions of continuous wetting

    E-print Network

    Pike, Adam Matthew

    2007-04-25

    This thesis research investigated the predictive performance of pavement marking retroreflectivity measured under various conditions of continuous wetting. The researcher compared nighttime detection distance of pavement markings in simulated rain...

  3. Evaluation of HMA moisture damage in Wisconsin as it relates to pavement performance

    Microsoft Academic Search

    K. Kanitpong; H. U. Bahia

    2008-01-01

    The Wisconsin Department of Transportation (WisDOT) has been using the tensile strength ratio (TSR) test (ASTM D-4867) to predict the potential susceptibility of asphalt mixture to moisture damage and other associated pavement deterioration. The objectives of this paper are to evaluate the relationship between the performance of asphalt pavements in the field and the TSR values measured in laboratory on

  4. Discussion on the Prediction Method of the Pavement Performance for Expressway

    Microsoft Academic Search

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

    2009-01-01

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

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

    SciTech Connect

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

    1998-08-01

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

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

    E-print Network

    Liu, Litao

    2013-09-23

    for developing performance prediction models for pavements that received preservation treatments. In this approach, the model consists of two tightly-coupled components: the first component is responsible for predicting the performance (e.g., IRI...

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

    E-print Network

    Liu, Litao

    2013-09-23

    for developing performance prediction models for pavements that received preservation treatments. In this approach, the model consists of two tightly-coupled components: the first component is responsible for predicting the performance (e.g., IRI...

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

    E-print Network

    Strategic Research Plan #12;· Performance-Based Concrete Pavement Mix Design System · Performance-Based Design Guide for New and Rehabilitated Concrete Pavements · High-Speed Nondestructive Testing and Intelligent Construction Systems · Optimized Surface Characteristics for Safe, Quiet, and Smooth Concrete

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

    SciTech Connect

    NONE

    1998-08-01

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

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

    E-print Network

    McGahan, Jeremy

    2006-04-12

    The physical characteristics of aggregates (form, angularity, and texture) are known to affect the performance of hot mix asphalt (HMA) pavements. Efforts to develop relationships between these aggregate characteristics ...

  11. An analysis of some properties of paving asphalts in Texas as they relate to pavement performance 

    E-print Network

    DuBose, Emmett Haygood

    1980-01-01

    PAVEMENT PERFORMANCE PROPERTIES ASPHALT BINDER PROPERTIES ASPHALT CONCRETE PROPERTIES EVALUATION OF THE RELATIONSHIP BETWEEN PAVEMENT PERFORMANCE AND ASPHALT BINDER PROPERTIES 4 DISCUSSION OF RESULTS INTRODUCTION Page 1V V111 10 10 25 25 29... contributions ( l, 4, 5, 6, 7). Their studies have led to a better understanding of the causative factors influencing the asphalt curing and hardening processes. There has been a great deal of study and speculation as to how these processes could...

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

    SciTech Connect

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

    1997-03-01

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

  13. PROSES DESAIN STRUKTUR PERKERASAN LENTUR YANG MEMPERHITUNGKAN VARIASI MODULUS PERKERASAN AKIBAT PENGARUH TEMPERATUR Design Procedure of Flexible Pavement Structures by Analyzing Pavement Modulus Variation due to Temperature Effects

    Microsoft Academic Search

    Djunaedi Kosasih

    The effects of pavement temperature on pavement modulus, particularly the asphalt layer modulus, are quite apparent. In the analytical design method, the effects of pavement temperature can be taken into account in term of design temperature factor, as that proposed by the Nottingham method. Alternatively as proposed by the Asphalt Institute method, Miner's theory can also be applied to calculate

  14. PERFORMANCE-BASED CONTRACTING IN CONSTRUCTION PHASE AND MAINTENANCE PHASE OF PAVEMENT

    NASA Astrophysics Data System (ADS)

    Yoshida, Takeshi

    Performance-based contracting for pavement in Japan started as performance warranties in construction phase, in 1999. Recently, road agencies have recognized the applicability of this type of contracting in outsourcing of maintenance activities. The objectives of this study are to clarify the issues of performance specifying in construction phase and maintenance phase of pavement, and to propose measures to be taken. This paper, with the recognition that the life of each pavement depends on performance standards for various attributes, reviews domestic and foreign examples of performance-based contracting. A performance standard based on the average of current practices can enhance product quality and service life with a warranty contract. Repair thresholds and response time for each deficiency should be considered as performance standards in maintenance phase.

  15. Accelerated performance testing of concrete pavement with short slabs

    Microsoft Academic Search

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

    2011-01-01

    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

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

    Microsoft Academic Search

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

    1999-01-01

    This report is one of a series of reports prepared as part of a recent study sponsored by the Federal Highway Administration (FHWA) aimed at updating the state-of-the-art of the design, construction, maintenance, and rehabilitation of continuous reinforced concrete (CRC) pavements. The scope of work of the FHWA study included the following: (1) Conduct of a literature review and preparation

  17. An analysis of some properties of paving asphalts in Texas as they relate to pavement performance

    E-print Network

    DuBose, Emmett Haygood

    1980-01-01

    for the degree of MASTER OF SCIENCE August, 1980 Major Subject: Civil Engineering AN ANALYSIS OF SOME PROPERTIES OF PAVING ASPHALTS IN TEXAS AS THEY RELATE TO PAVEMENT PERFORMANCE A Thesis by EMMETT HAYGOOD DUBOSE, JR. Approved as to style and content by...: ai a o ommittee Member Member Head of Department August, 1980 119 r@~ ABSTRACT An Analysis of Some Propert1es of Pav1ng Asphalts in Texas as They Relate to Pavement Performance. (August, 1980) Emmett Haygood DuBose, Jr. , B. S. , Texas ABH...

  18. Practical approach for designing flexible pavements using recycled roadway materials as base course

    Microsoft Academic Search

    Ali Ebrahimi; Brian R. Kootstra; Tuncer B. Edil; Craig H. Benson

    2012-01-01

    Resilient modulus and plastic deformation of two recycled base course materials, recycled pavement material (RPM) and road surface gravel (RSG) and natural aggregate (Class 5), were investigated using a large-scale model experiment (LSME) and laboratory bench-scale resilient modulus (BSRM) tests. The RPM and RSG were tested alone and with 10% by weight Class C fly ash. The LSME tests indicate

  19. 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...

  20. New Concept of Prolonging the Service Life-Span for Asphalt Pavement of Expressways - Theory and Method of Swingy Lane Line on Flexible Pavement of Expressways

    Microsoft Academic Search

    Zhi Wang; Dian-liang Xiao

    2009-01-01

    How to prolong the service life-span for asphalt pavement of expressways has become a hot subject for many scientific workers. The author in this paper, after examining the commonly-seen manifestations of the asphalt pavement diseases and the track distribution laws from the vehicle tires on expressways, puts forward some new approaches and concepts for prolonging the service life-span for asphalt

  1. Assessment of the performance of rigid pavement back-calculation through finite element modeling

    NASA Astrophysics Data System (ADS)

    Shoukry, Samir N.; William, Gergis W.; Martinelli, David R.

    1999-02-01

    This study focuses on examining the behavior of rigid pavement layers during the Falling Weight Deflectometer (FWD) test. Factors affecting the design of a concrete slab, such as whether the joints are doweled or undoweled and the spacing between the transverse joints, were considered in this study. Explicit finite element analysis was employed to investigate pavement layers' responses to the action of the impulse of the FWD test. Models of various dimensions were developed to satisfy the factors under consideration. The accuracy of the finite element models developed in this investigation was verified by comparing the finite element- generated deflection basin with that experimentally measured during an actual test. The results showed that the measured deflection basin can be reproduced through finite element modeling of the pavement structure. The resulting deflection basins from the use FE modeling was processed in order to backcalculate pavement layer moduli. This approach provides a method for the evaluation of the performance of existing backcalculation programs which are based on static elastic layer analysis. Based upon the previous studies conducted for the selection of software, three different backcalculation programs were chosen for the evaluation: MODULUS5.0, EVERCALC4.0, and MODCOMP3. The results indicate that ignoring the dynamic nature of the load may lead to crude results, especially during backcalculation procedures.

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

    PubMed

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

    2011-01-01

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

  3. Forensic investigation of failed airfield test pavements

    Microsoft Academic Search

    Kasthurirangan Gopalakrishnan

    2010-01-01

    Field and laboratory forensic studies were conducted to investigate the failure mechanisms of four different flexible test\\u000a pavement sections at the Federal Aviation Administration's National Airport Pavement Test Facility (NAPTF), a state-of-the-art\\u000a full scale pavement test facility dedicated solely to airport pavement research. The first set of test pavements constructed\\u000a at the NAPTF included a total of nine test sections

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

    Microsoft Academic Search

    Benjamin O. Brattebo; Derek B. Booth

    2003-01-01

    This study examined the long-term effectiveness of permeable pavement as an alternative to traditional impervious asphalt pavement in a parking area. Four commercially available permeable pavement systems were evaluated after 6 years of daily parking usage for structural durability, ability to infiltrate precipitation, and impacts on infiltrate water quality. All four permeable pavement systems showed no major signs of wear.

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

    E-print Network

    Rushing, John Ford

    2014-04-25

    test, the dynamic modulus test, and the Asphalt Pavement Analyzer (APA) test as potential performance tests to accompany airport HMA mixture design with a goal of providing acceptable threshold test results that predict rutting performance under...

  6. Investigation of Noise and Durability Performance Trends for Asphaltic Pavement Surface Types: Three-Year Results

    Microsoft Academic Search

    Qing Lu; Erwin R. Kohler; John T Harvey; Aybike Ongel

    2009-01-01

    The work presented in this report is part of an on-going research project, whose central purpose is to support the Caltrans Quieter Pavement Research Program, that has as its goals and objectives the identification of quieter, smoother, safer and more durable pavement surfaces. The research has been carried out as part of Partnered Pavement Research Center Strategic Plan Element 4.19

  7. Winter Performance and Maintenance of Porous Asphalt Pavements

    E-print Network

    Concrete (HSG-B)Porous Asphalt (HSG-C) #12;Cold Climate Performance Results #12;12 Porous Asphalt Surface of Zero Ice tolerance Porous asphalt is not a silver bullet 15 #12;16 Why are we concerned about chloride ? No stormwater treatment removes chloride 6 chloride TMDLs nationwide Usage is on the rise Need for public safety

  8. General outlook of pavement and vehicle dynamics

    SciTech Connect

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

    1997-11-01

    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.

  9. Advances in the design of pavement surfaces

    Microsoft Academic Search

    William Aage Johnsen

    1998-01-01

    The objective is to advance the design of pavement surfaces. The goal is to design a pavement with low wear and high friction for tires. The objective is accomplished by relating the pavement texture to its performance and finishing technique. Pavement texture is represented by characterization parameters calculated from topographic data sets. Data sets are acquired using a Scanning Laser

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

    PubMed

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

    2014-01-01

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

  11. Hot-mix recycling of asphalt concrete airfield pavements

    Microsoft Academic Search

    Tere A. DeMoss

    2005-01-01

    The hot-mix recycling of existing airfield pavements is cost effective and can produce asphalt concrete mixtures with material properties equivalent to those of new materials for airfield pavements. Recycled pavement mixes from four different airfields were investigated for performance and current material properties compared to the original or “as constructed” properties. Pavement samples were obtained from each recycled pavement. Properties

  12. Using finite element analysis of retroreflective raised pavement markers to recommend testing procedures for simulating their field performance 

    E-print Network

    Agrawal, Ravi Prakash

    2006-08-16

    Pad Properties ..............................................................48 6. Post-calibration RRPM Type A Material Properties .................................................52 7. Post-calibration RRPM Type B Material Properties... of the RRPMs suggests that their performance has been degrading over the years (2, 3, 4, 5). Arguably, major problems associated with RRPMs are structural damage while installed, poor adhesion to pavements, and loss of retroreflectivity over time...

  13. Effect of Recycling Rate and Asphalt Binder on the Performance of Recycled Asphalt Concrete for Airport Pavement Rehabilitation

    Microsoft Academic Search

    Kai Su; Yoshitaka Hachiya; Ryota Maekawa

    2009-01-01

    Aimed to prompt the extensive use of reclaimed asphalt aggregate (RAA) in airport pavement rehabilitation, a series of laboratory tests are conducted to intensively evaluate the effect of recycling rate and asphalt binder on the performances of recycled asphalt concrete (RAC). The results indicate that rutting resistance of RAC using either straight or modified asphalt binder increases with the increase

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

    E-print Network

    Vandenbossche, Julie M.

    Recycled Concrete Aggregates GREGORY D. CUTTELL, MARK B. SNYDER, JULIE M. VANDENBOSSCHE, AND MONTY J. WADE designed and constructed rigid pavements containing recycled concrete aggregate (RCA). Success has been the recycled pavements that incorporated RCA derived from concrete affected by D-cracking and alkali

  15. Influence of Recycled Asphalt Pavement on Fatigue Performance of Asphalt Concrete Base Courses

    Microsoft Academic Search

    Amir Tabakovic?; Amanda Gibney; Ciaran McNally; Michael D. Gilchrist

    2010-01-01

    This paper presents the physical properties of recycled asphalt pavement RAP and its influence on the mechanical perfor- mance of a binder course asphalt pavement mix. A series of binder course mixes were designed containing varying percentages of RAP. A mix made from only virgin material was selected as the control mix for the investigation. The effect of introducing RAP

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

    E-print Network

    Neshvadian Bakhsh, Keivan

    2014-08-11

    of governing distress types that eventually deteriorates the pavement structure and decreases the pavement service life. Effectiveness of joint sealants to protect jointed concrete pavement against water related distresses has been a focus of great interest...

  17. Extending Flexible Pavement Life

    Microsoft Academic Search

    Jim Penman; Joe Cavanaugh

    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

  18. 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...

  19. Binzhou Perpetual Pavement Test Road

    Microsoft Academic Search

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

    2009-01-01

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

  20. SOURCE: UNIVERSITY OF CALIFORNIA PAVEMENT RESEARCH CENTER PAVEMENT TECHNOLOGY UPDATE

    E-print Network

    California at Berkeley, University of

    , and technologies through partnership between academia, Caltrans, and industry. Introduction The Asphalt Pavement-life pavements are low life-cycle cost, low user-delay costs, reduced environmental impact, and greater worker: design, materials and testing, communication, construction, and performance. Design The design of long

  1. Development of a fiber optic pavement subgrade strain measurement system

    Microsoft Academic Search

    Craig Emerson Miller

    2000-01-01

    This dissertation describes the development of a fiber optic sensing system to measure strains within the soil subgrade of highway pavements resulting from traffic loads. The motivation to develop such a device include improvements to: (1)all phases of pavement design, (2)theoretical models used to predict pavement performance, and (3)pavement rehabilitation. The design of the sensing system encompasses selecting an appropriate

  2. An investigation into the predictive performance of pavement marking retroreflectivity measured under various conditions of continuous wetting 

    E-print Network

    Pike, Adam Matthew

    2007-04-25

    . The researcher measured the retroreflectivity of 18 pavement marking samples under 14 different conditions. The American Society for Testing and Materials (ASTM) has three standards for measuring the retroreflectivity of pavement markings under: dry (E-1710...

  3. High-Performance Flexible Waveguiding Photovoltaics

    PubMed Central

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

    2013-01-01

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

  4. ANALYSIS OF SHEAR STRESS IN ASPHALT PAVEMENTS UNDER ACTUAL MEASURED TIRE-PAVEMENT CONTACT PRESSURE

    Microsoft Academic Search

    Kai SU; Lijun SUN; Yoshitaka HACHIYA; Ryota MAEKAWA

    Rutting is one of the most important load-induced distresses found in asphalt pavements. The primary mechanism of rutting is associated with shear deformation rather than densification. Recently, top-down cracking probably attributed to shear failure has also been a frequent occurrence in asphalt pavements. Clearly, shear stress is one of the critical factors affecting pavements performance, and there is a great

  5. Concrete Pavement Performance and Research at the Minnesota Road Research Project - The First Ten Years

    Microsoft Academic Search

    Thomas Burnham

    The Minnesota Road Research (MnROAD) facility was constructed in the early 1990's to include fourteen plain jointed concrete pavement test sections. Nine of the test sections are interstate highway designs with design lives of 5 or 10 years. The other five test sections are low-volume road designs. With traffic loading beginning in 1994, the test sections have now experienced over

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

    PubMed Central

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

    2014-01-01

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

  7. Comparative Economic-Engineering Evaluation of Concrete Block Pavements

    Microsoft Academic Search

    Ilan Ishai

    2003-01-01

    This paper presents a comparative engineering-economical evaluation and analysis of flexible, rigid, and Concrete Block Pavements (CBP) at different structure alternatives. Several key factors were involved in the analysis. They are: three types of traffic categories—Occasional, Medium, and Very Heavy; one subgrade strength (CBR=4%); local pavement design practice (current design curves for flexible, rigid and CBP pavements); consideration of both

  8. Development of Pavement Temperature Contours for India

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

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

    PubMed

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

    2014-01-01

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

  10. Performance of an enhanced pervious pavement system loaded with large volumes of hydrocarbons.

    PubMed

    Newman, Alan P; Puehmeier, Tim; Shuttleworth, Andy; Pratt, Christopher J

    2014-01-01

    Five litres of lubricating oil and two 8.5 litre batches of diesel were deposited on each of two hydraulically isolated experimental enhanced pervious pavement parking bays. The 50 mm aggregate subbases of the two bays were of either recycled concrete or crushed limestone. The bays were constructed in such a way that a near-surface gravity separator was created by the arranging of the outlet pipes such that a permanent pool of water was maintained in the system and water could only enter from below the level of any floating oil. Dissolved/dispersed hydrocarbons were measured at acceptable concentrations when monitoring was carried out over a period of approximately 5 months. The maximum concentration was 7.2 mg/l and of all the samples collected only 3% exceeded the 5 mg/l limit applied in the UK for a class 1 interceptor, and the majority of samples had hydrocarbon concentrations of less than 2 mg/l. Much more significant is the fact that no free product was discharged from either system up to the time the experiment was dismantled 2 years from the first oil application despite the fact that sufficient hydrocarbon had been added to each pavement to produce a film on a water surface of over 500 hectares. PMID:25225930

  11. Strength and deformation characteristics of pavements

    NASA Astrophysics Data System (ADS)

    Shook, J. F.; Kallas, B. F.; McCullough, B. F.; Taute, A.; Rada, G.; Witczak, M. W.; Heisey, J. S.; Stokoe, K. H.; Meyer, A. H.; Huffman, M. S.

    The Colorado experimental base project was a full-scale field experment constructed with various thicknesses of two full depth hot mix sand asphalt beans, one full depth asphalt concrete base, and one thickness of a standard design with untreated base and subbase layers. Relative thicknesses of one asphalt concrete base, two hot mix sand asphalt bases, and one standard design with untreated base and subbase required to give an equal level of pavement performance were determined. Certain measured properties of the pavement and the pavement components were related to observed levels of performance by using both empirical and theoretical models for pavement behavior.

  12. Application Performance and Flexibility on Exokernel Systems

    Microsoft Academic Search

    M. Frans Kaashoek; Dawson R. Engler; Gregory R. Ganger; Héctor M. Briceño; Russell Hunt; David Mazières; Thomas Pinckney; Robert Grimm; John Jannotti; Kenneth Mackenzie

    1997-01-01

    The exokernel operating system architecture safely gives untrusted software efficient control over hardware and software resources by separating management from protection. This paper describes an exokernel system that allows specialized applications to achieve high performance without sacrificing the performance of unmod- ified UNIX programs. It evaluates the exokernel architecture by measuring end-to-end application performance on Xok, an exo- kernel for

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

    Microsoft Academic Search

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

  14. Semiconducor wires and ribbons for high performance flexible electronics

    Microsoft Academic Search

    Y. Sun; A. J. Baca; J.-H. Ahn; E. Menard; H.-S Kim; W. Choi; D.-H Kim; Y. Huang

    2008-01-01

    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,

  15. Analytical performance models for closed-loop flexible assembly systems

    Microsoft Academic Search

    Manjunath Kamath; Rajan Suri; Jerry L. Sanders

    1988-01-01

    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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  17. Flexible Clusters for High-Performance Computing

    Microsoft Academic Search

    Paolo Anedda; Massimo Gaggero; Giovanni Busonera; Omar Schiaratura; Gianluigi Zanetti

    2010-01-01

    High Performance Computational Clusters are, in general, rather rigid objects that present to their user a limited number of degrees of freedom related, usually, only to the specification of the resources requested and to the selection of specific applications and libraries. While in standard production environments this is reasonable and actually desirable, it can become an hindrance when one needs

  18. Rehabilitation of continuously reinforced concrete pavements using overlays 

    E-print Network

    Sriraman, Soumya

    1993-01-01

    overlay using CRC was laid on a 6 inch thick 28 jointed plain concrete pavement and which had previously been overlaid with 3. 5 inches of asphalt concrete. The primary purpose of the overlay was to strengthen the existing pavement and improve... in the design and performance of CRC overlays or overlays on CRC pavements. Climate and fatigue are other factors identified in literature as causative for the development of failures like rutting (predominant in AC overlays of CRC pavements), and reflective...

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

    Microsoft Academic Search

    Gary Lee Anderton

    1997-01-01

    The research study described in this report focuses on determining the engineering properties of the resin modified pavement (RMP) material relating to pavement performance, and then developing a rational mechanistic design procedure to replace the current empirical design procedure. A detailed description of RMP is provided, including a review of the available literature on this relatively new pavement technology. Field

  20. THREE DIMENSIONAL FINITE ELEMENT MODELING OF PAVEMENT SUBSURFACE DRAINAGE SYSTEMS

    Microsoft Academic Search

    Yinhui Liu

    2005-01-01

    Pavement subsurface drainage systems (PSDS) are designed to drain the entrapped water out of pavement. To investigate the effects of various factors on the performance of PSDS, three dimensional models were developed using the finite element method to simulate the unsaturated drainage process in pavement. The finite element models were calibrated using the field information on outflow, peak flow, layer

  1. CONCRETE PAVEMENT Reference Manual

    E-print Network

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

  2. Electrical performance of inkjet printed flexible cable for ECG monitoring

    Microsoft Academic Search

    Qiansu Wan; Geng Yang; Qiang Chen; Li-Rong Zheng

    2011-01-01

    This paper presents electrical performance of paper based inkjet printed flexible cable for wearable electrocardiogram (ECG) monitoring. The cable is fabricated by inkjet printing of nano-silver wires on paper which connect bio-electric electrodes with wireless transmission of ECG signals to the central medical device. The cable consists of printed metal traces and a shielding line in the middle. The experiment

  3. Utilization of Advanced Diagnostic Methods for Texture and Rut Depth Analysis on a Testing Pavement Section

    NASA Astrophysics Data System (ADS)

    Slabej, Martin; Grin?, Michal; Kotek, Peter; Ková?, Matúš; Decký, Martin

    2015-05-01

    Qualitative characteristics of pavement in wide range reflects the pavement serviceability, which is a summary of the characteristics of the pavement, providing a fast, smooth, economical and especially safe driving of motor-vehicles. The target factor of pavement serviceability and safety of roads represents the quality of their surface properties. In the framework of research activities performed in the Research Centre founded under the auspices of University of Žilina, individual parameters of pavement serviceability were monitored by pavement surface scanning. This paper describes the creation of a 3D - road surface model and its analysis and evaluation from the viewpoint of two pavement serviceability parameters - the rut depth and texture. Measurements were performed on an experimental pavement section used contemporary in an Accelerated Pavement Testing experiment. The long-term goal is to ascertain functions predicting degradation of these two pavement serviceability parameters.

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

    SciTech Connect

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

    2011-02-05

    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.

  5. Flexible high-performance carbon nanotube integrated circuits

    Microsoft Academic Search

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

    2011-01-01

    Carbon nanotube thin-film transistors are expected to enable the fabrication of high-performance, flexible and transparent devices using relatively simple techniques. However, as-grown nanotube networks usually contain both metallic and semiconducting nanotubes, which leads to a trade-off between charge-carrier mobility (which increases with greater metallic tube content) and on\\/off ratio (which decreases). Many approaches to separating metallic nanotubes from semiconducting nanotubes

  6. Light Weight and Flexible High-Performance Diagnostic Platform.

    PubMed

    Karnaushenko, Daniil; Ibarlucea, Bergoi; Lee, Sanghun; Lin, Gungun; Baraban, Larysa; Pregl, Sebastian; Melzer, Michael; Makarov, Denys; Weber, Walter M; Mikolajick, Thomas; Schmidt, Oliver G; Cuniberti, Gianaurelio

    2015-07-01

    A flexible diagnostic platform is realized and its performance is demonstrated for early detection of avian influenza virus (AIV) subtype H1N1 DNA sequences. The key component of the platform is high-performance biosensors based on high output currents and low power dissipation Si nanowire field effect transistors (SiNW-FETs) fabricated on flexible 100 ?m thick polyimide foils. The devices on a polymeric support are about ten times lighter compared to their rigid counterparts on Si wafers and can be prepared on large areas. While the latter potentially allows reducing the fabrication costs per device, the former makes them cost efficient for high-volume delivery to medical institutions in, e.g., developing countries. The flexible devices withstand bending down to a 7.5 mm radius and do not degrade in performance even after 1000 consecutive bending cycles. In addition to these remarkable mechanical properties, on the analytic side, the diagnostic platform allows fast detection of specific DNA sequences of AIV subtype H1N1 with a limit of detection of 40 × 10(-12) m within 30 min suggesting its suitability for early stage disease diagnosis. PMID:25946521

  7. Impact of Traffic Data on the Pavement Distress Predictions using the Mechanistic Empirical Pavement Design Guide

    Microsoft Academic Search

    Sue Ahn; Srivatsav Kandala; J. Uzan; Mohamed El-Basyouny

    2011-01-01

    This study examines the adequacy of using conventional traffic data and national default values in the absence of weigh-in-motion (WIM) data for pavement design. A comparative study was conducted on 14 unique sections in Arizona (AZ), where WIM data are available through the Long Term Pavement Performance (LTPP) program. The study consists of two parts: 1) comparisons of input traffic

  8. Flexible body dynamic stability for high performance aircraft

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  9. Quantitative analysis of microtubule orientation in interdigitated leaf pavement cells.

    PubMed

    Akita, Kae; Higaki, Takumi; Kutsuna, Natsumaro; Hasezawa, Seiichiro

    2015-05-01

    Leaf pavement cells are shaped like a jigsaw puzzle in most dicotyledon species. Molecular genetic studies have identified several genes required for pavement cells morphogenesis and proposed that microtubules play crucial roles in the interdigitation of pavement cells. In this study, we performed quantitative analysis of cortical microtubule orientation in leaf pavement cells in Arabidopsis thaliana. We captured confocal images of cortical microtubules in cotyledon leaf epidermis expressing GFP-tubulin? and quantitatively evaluated the microtubule orientations relative to the pavement cell growth axis using original image processing techniques. Our results showed that microtubules kept parallel orientations to the growth axis during pavement cell growth. In addition, we showed that immersion treatment of seed cotyledons in solutions containing tubulin polymerization and depolymerization inhibitors decreased pavement cell complexity. Treatment with oryzalin and colchicine inhibited the symmetric division of guard mother cells. PMID:26039484

  10. Performance-based design and analysis of flexible composite propulsors

    NASA Astrophysics Data System (ADS)

    Motley, Michael R.; Young, Yin L.

    2011-11-01

    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.

  11. An Asset Management Framework Based on Field Performance of Pavement Markings 

    E-print Network

    Madiri, Sam

    2011-08-08

    . Sectional assessment and management methods were proposed as a part of a practical restriping methodology. An information tool was developed in a geographic information system (GIS) environment as an application. Retroreflectivity was the only performance...

  12. Assessment of durability performance of "Early-Opening-to-Traffic" Portland Cement Concrete pavement and patches

    E-print Network

    Shrestha, Pradhumna Babu

    1999-01-01

    PERFORMANCE TRENDS, AND UTILITY ASSESSMENT TABLES . . . . . . I 1 2 129 APPENDIX B APPENDIX C VITA UTILITY CURVES FOR PERFORMANCE, PRACTICALITY, AND COST OF EOT PCC... . . . . . , . . . . . . . . . . 109 C. I Utility Curve for Freeze/Thaw . C. 2 Utility Curve for Drying Shrinkage C. 3 Utility Curve for Chemical Attack C. 4 Utility Curve for Fatigue Strength C. 5 Utility Curve for Abrasion Strength . C. 6 Utility Curve for Volumeiric Change...

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

    Microsoft Academic Search

    Kamalesh Panthi

    2009-01-01

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

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

    Microsoft Academic Search

    Kamalesh Panthi

    2009-01-01

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

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

    E-print Network

    McGahan, Jeremy

    2006-04-12

    .8 6.3 0.2 12 64-40 RHY 0.335 0.31 1.5 3.8 1.6 The next performance parameter is E*/sin f at a frequency of 10 Hz. This value incorporates the dynamic modulus E* and the phase angle f. Dynamic modulus is the ratio of amplitude stress...

  16. Identification of asphalt binder properties that affect cracking performance of hot mixed asphalt concrete pavements

    E-print Network

    Hastings, Charles Patrick

    1997-01-01

    Institute (TTI) from the construction projects in Texarkana and Sherman. Penetration @ 25'C (ASTM D5), and capillary viscosity tests @ 60'C (ASTM D 2171) and 135'C (ASTM D 2170) were performed on the binders at the beginning of the study in 1987... the results (a) for penetration (ASTM D 5) differ by more than 8 units of their mean; (b) for viscosity 60'C (ASTM D 2171) differ by more than 10/0 of their mean; or (c) for viscosity 135'C (ASTM D 2170) differ by more than 3. 15o of their mean...

  17. 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...

  18. Advancement of Erosion Testing, Modeling, and Design of Concrete Pavement Subbase Layers 

    E-print Network

    Jung, Youn Su

    2010-10-12

    in a concrete pavement system. The erosion of material beneath a concrete slab is an important performance-related factor that if applied to the selection of base materials can enhance the overall design process for concrete pavement systems. However...

  19. Performance and system flexibility of the CDF Hardware Event Builder

    SciTech Connect

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

    1991-11-01

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

  20. Performance and system flexibility of the CDF Hardware Event Builder

    SciTech Connect

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

    1991-11-01

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

  1. Advances in the design of pavement surfaces

    NASA Astrophysics Data System (ADS)

    Johnsen, William Aage

    The objective is to advance the design of pavement surfaces. The goal is to design a pavement with low wear and high friction for tires. The objective is accomplished by relating the pavement texture to its performance and finishing technique. Pavement texture is represented by characterization parameters calculated from topographic data sets. Data sets are acquired using a Scanning Laser Position Sensor (SLPS, Johnsen 1995) capable of measuring over a 150 x 150 x 50 mm (x, y, z) volume, at a resolution of 25 mum on each axis. Standard and scale-sensitive fractal analysis methods are used and a computer model is developed to calculate characterization parameters from the topographic data sets. The fractal parameters complexity (ASFC) and smooth-rough crossover (SRC) are able to differentiate certain pavement textures. The computer model, when constrained to various settings, correlates with the ASTM E965 sand-patch volumetric technique with a slope of 1.156 ± 0.247 and a correlation coefficient (rsp2) of 0.961 ± 0.016. Neural networks are used to relate pavement texture to in-situ performance. Nearly 75% of the neural network input arrays can predict the friction coefficient with a correlation coefficient of greater than 0.90. The parameters ASFC and SRC increase, and mean texture depth measurements made by a van or the beam method (MTDVB) decrease, this statistical significance. A new device is developed to measure 2500 coefficients of friction per second to investigate friction and wear of tires over a 60 millisecond impact on varying pavement specimens. The mean and standard deviation of the measured coefficient of friction curves differentiate the direction of the pavement brush finish. It is shown that low wear rates are possible with high coefficients of friction.

  2. Optical performance monitoring for dynamic and flexible photonic networks

    NASA Astrophysics Data System (ADS)

    Oda, Shoichiro; Yang, Jeng-Yuan; Akasaka, Youichi; Vassilieva, Olga; Yamauchi, Tomohiro; Aoki, Yasuhiko; Sekiya, Motoyoshi; Rasmussen, Jens C.

    2015-01-01

    Optical performance monitoring (OPM) is considered as an important tool in order to operate and manage dynamic, flexible, and thus complex photonic networks. In this paper, firstly we review recent studies on OPM and discuss its possible applications, such as failure diagnosis of transmitter, receiver, and other transport equipment, optimization of system reach design, and so on. We then present two different types of in-band OSNR monitor, consisting of an optical bandpass filter, a photo-detector, and a signal processer. Since the proposed monitor might be realized by the same hardware implementation as an optical channel monitor (OCM), this is potentially integrated with an OCM in a low-cost fashion. We also explain a BER monitor, which is realized by the same hardware configuration as the above in-band OSNR monitor. The BER in the method is estimated by monitoring OSNR including nonlinear noise as noise source and taking the imperfection of Tx, Rx, and other equipment into account. Finally we develop FPGA-based optical performance monitor prototype and experimentally demonstrate successful monitoring performance.

  3. Precast Concrete Pavement for Intermittent Concrete Pavement Repair Applications

    Microsoft Academic Search

    Shiraz Tayabji; Neeraj Buch; Erwin Kohler

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

  4. Advanced self-healing asphalt composites in the pavement performance field: mechanisms at the nano level and new repairing methodologies.

    PubMed

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

    2015-01-01

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

  5. Concrete Pavement Surface Characteristics

    E-print Network

    Improving Concrete Pavement Surface Characteristics Pooled Fund TPF-5(139) National Concrete, Broom, Belt, Carpet) Shot Peened Exposed Aggregate Porous (Pervious) Concrete Milled HMA and Surface do with this knowledge? #12;Better Design and Construction Practices for Texturing Concrete Pavement

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

    NASA Astrophysics Data System (ADS)

    Reyff, James A.; Donavan, Paul

    2005-09-01

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

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

    E-print Network

    Zornberg, Jorge G.

    is typically as- phalt concrete, which is a bituminous hot-mix aggregate (HMA) obtained from distillation, pavement, design ABSTRACT: Geosynthetics have been used to reinforce the base layer of flexible pavement of design pa- rameters for geosynthetics has been complicated by the difficulty in associating

  8. Pervious Pavement System Evaluation

    EPA Science Inventory

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

  9. Automated pavement crack detection 

    E-print Network

    Rao, Ashok Madhava

    1991-01-01

    AUTOMATED PAVEMENT CRACK DETECTION A Thesis by ASHOK MADHAVA RAO Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1991 Major Subject...: Electrical Engineering AUTOMATED PAVEMENT CRACK DETECTION A Thesis by ASHOK MADHAVA RAO Approved as to style and content by . c Norman C. Grisw d (Chair of Committ ) Nasser Kehtarnavaz (Member) g, J~, Karan Watson Robert L. Lytt (Member) Jo W...

  10. Performance of thin film silicon MEMS on flexible plastic substrates

    Microsoft Academic Search

    S. B. Patil; V. Chu; J. P. Conde

    2008-01-01

    The fabrication and characterization of thin film silicon MEMS microbridges on flexible polyethylene terephthalate substrates are described. Surface micromachining using an aluminum sacrificial layer and a maximum processing temperature of 110°C was used for device fabrication. These microbridges are electrostatically actuated and their deflection at resonance and at low frequencies is measured optically. Quasi-DC deflection with a quadratic dependence of

  11. The performance impact of flexibility in the Stanford FLASH multiprocessor

    Microsoft Academic Search

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

    1994-01-01

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

  12. 4/28/2010 1Porous Pavements Porous Pavements

    E-print Network

    Minnesota, University of

    Aichinger Ramsey-Washington Metro Watershed District #12;4/28/2010 2Porous Pavements Porous Pavements Why am I talking about this topic: · I am not an engineer. · I am a water resources planner and watershed by many City and Watershed rules and may become a requirement of state rules Benefits of Porous Pavement

  13. FRP Dowels for Concrete Pavements

    E-print Network

    to the expansion of steel during the corrosion process. A corrosion-free alternative, such as Fiber Reinforced currently used for highway pavement could cause severe deterioration of concrete highway pavements due

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    E-print Network

    Cardin, Michel-Alexandre, 1979-

    2011-01-01

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

  17. Investigation of roller-integrated compaction monitoring and in-situ testing technologies for characterization of pavement foundation layers

    Microsoft Academic Search

    Pavana Kumar Reddy Vennapusa

    2008-01-01

    The performance and durability of pavement structures depend heavily on the pavement foundation layer support conditions. Construction of pavement foundation layers with adequate support capacities require use of proper construction methods, and following proper quality control (QC) and quality assurance (QA) procedures. There has been growing interest in the United States for incorporating roller-integrated compaction monitoring technologies and various in-situ

  18. Evaluation of a highway pavement using non destructive tests: Falling Weight Deflectometer and Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Marecos, Vania; Fontul, Simona; de Lurdes Antunes, Maria

    2015-04-01

    This paper presents the results of the application of Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) to assess the bearing capacity of a rehabilitated flexible highway pavement that began to show the occurrence of cracks in the surface layer, about one year after the improvement works. A visual inspection of the surface of the pavement was performed to identify and characterize the cracks. Several core drills were done to analyse the cracks propagation in depth, these cores were also used for GPR data calibration. From the visual inspection it was concluded that the development of the cracks were top-down and that the cracks were located predominantly in the wheel paths. To determine the thickness of the bituminous and granular layers GPR tests were carried out using two horn antennas of 1,0 GHz and 1,8 GHz and a radar control unit SIR-20, both from GSSI. FWD load tests were performed on the wheel paths and structural models were established, based on the deflections measured, through back calculation. The deformation modulus of the layers was calculated and the bearing capacity of the pavement was determined. Summing up, within this study the GPR was used to continuously detect the layer thickness and the GPR survey data was calibrated with core drills. The results showed variations in the bituminous layer thickness in comparison to project data. From the load tests it was concluded that the deformation modulus of the bituminous layers were also vary variable. Limitations on the pavement bearing capacity were detected in the areas with the lower deformation modulus. This abstract is of interest for COST Action TU1208 Civil Engineering Applications of Ground Penetrating Radar.

  19. Combined permeable pavement and ground source heat pump systems 

    E-print Network

    Grabowiecki, Piotr

    2010-01-01

    The PhD thesis focuses on the performance assessment of permeable pavement systems incorporating ground source heat pumps (GSHP). The relatively high variability of temperature in these systems allows for the survival of pathogenic organisms within...

  20. Incorporating uncertainty in the Life Cycle Cost Analysis of pavements

    E-print Network

    Swei, Omar Abdullah

    2012-01-01

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

  1. High-performance green flexible electronics based on biodegradable cellulose nanofibril paper

    PubMed Central

    Jung, Yei Hwan; Chang, Tzu-Hsuan; Zhang, Huilong; Yao, Chunhua; Zheng, Qifeng; Yang, Vina W.; Mi, Hongyi; Kim, Munho; Cho, Sang June; Park, Dong-Wook; Jiang, Hao; Lee, Juhwan; Qiu, Yijie; Zhou, Weidong; Cai, Zhiyong; Gong, Shaoqin; Ma, Zhenqiang

    2015-01-01

    Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials. PMID:26006731

  2. High-performance green flexible electronics based on biodegradable cellulose nanofibril paper.

    PubMed

    Jung, Yei Hwan; Chang, Tzu-Hsuan; Zhang, Huilong; Yao, Chunhua; Zheng, Qifeng; Yang, Vina W; Mi, Hongyi; Kim, Munho; Cho, Sang June; Park, Dong-Wook; Jiang, Hao; Lee, Juhwan; Qiu, Yijie; Zhou, Weidong; Cai, Zhiyong; Gong, Shaoqin; Ma, Zhenqiang

    2015-01-01

    Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials. PMID:26006731

  3. Large-scale integration of semiconductor nanowires for high-performance flexible electronics.

    PubMed

    Liu, Xi; Long, Yun-Ze; Liao, Lei; Duan, Xiangfeng; Fan, Zhiyong

    2012-03-27

    High-performance flexible electronics has attracted much attention in recent years due to potential applications in flexible displays, artificial skin, radio frequency identification, sensor tapes, etc. Various materials such as organic and inorganic semiconductor nanowires, carbon nanotubes, graphene, etc. have been explored as the active semiconductor components for flexible devices. Among them, inorganic semiconductor nanowires are considered as highly promising materials due to their relatively high carrier mobility, reliable control on geometry and electronic properties, and cost-effective synthesis processes. In this review, recent progress on the assembly of high-performance inorganic semiconductor nanowires and their applications for large-scale flexible electronics will be summarized. In particular, nanowire-based integrated circuitry and high-frequency electronics will be highlighted. PMID:22364279

  4. Sustainable Concrete Pavements: A Manual of Practice

    E-print Network

    #12;#12;#12;Sustainable Concrete Pavements: A Manual of Practice January 2012 TECHNICAL EDITORS Dr. Peter Taylor, Associate Director National Concrete Pavement Technology Center, Iowa State Taylor, Associate Director National Concrete Pavement Technology Center, Iowa State University Mr. Gary

  5. 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...

  6. Multidisciplinary structural design and optimization for performance, cost, and flexibility

    E-print Network

    Nadir, William David, 1979-

    2005-01-01

    Reducing cost and improving performance are two key factors in structural design. In the aerospace and automotive industries, this is particularly true with respect to design criteria such as strength, stiffness, mass, ...

  7. Performance, scalability, and flexibility in the RAW network router

    E-print Network

    DeGangi, Anthony M

    2004-01-01

    Conventional high speed Internet routers are built using custom designed microprocessors, dubbed network processors, to efficiently handle the task of packet routing. While capable of meeting the performance demanded of ...

  8. Effect of flexible working hours on employee satisfaction and performance: A field experiment

    Microsoft Academic Search

    Christopher Orpen

    1981-01-01

    64 federal workers were randomly assigned to flexible or fixed working hours, and after 6 mo they completed the Index of Job Satisfaction. In addition, their supervisors rated their 6-mo performance on a 9-point scale. Results indicate that flexitime caused a significant increase in worker satisfaction but had negligible effects on performance, whether assessed by output or ratings. Research should

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

    SciTech Connect

    Raad, L.; Saboundjian, S.

    1997-05-01

    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.

  10. 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...

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

    Microsoft Academic Search

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

    2009-01-01

    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

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

    PubMed Central

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

    2014-01-01

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

  13. Highly transparent and flexible triboelectric nanogenerators: performance improvements and

    E-print Network

    Wang, Zhong L.

    of the UV­ ozone treatment, surface properties, and surrounding environment on the output performance is probably due to the bond breaking of Si­O­Si groups, and is closely related to the surface properties by using polyester (PET) and polydimethylsi- loxane (PDMS) lms as exible substrates to integrate ITO

  14. ROBUST CONTROL DESIGN OF A HIGH PERFORMANCE FLEXIBLE ELECTROMECHANICAL SYSTEM

    E-print Network

    Massachusetts at Amherst, University of

    performance control systems. In contrast to such systems, small actuator drives such as compact disc and hard disc drive mechanisms, are easy to access with experiments. In these high­volume electronics controllers applied to a Compact Disc mechanism. The design objective is to achieve good track

  15. Solution-processed high-performance colloidal quantum dot tandem photodetectors on flexible substrates

    SciTech Connect

    Jiang, Zhenyu; You, Guanjun; Wang, Li; Liu, Jie; Xu, Jian, E-mail: jianxu@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Hu, Wenjia [China Tianchen Engineering Corporation, Tianjin 300400 (China); Zhang, Yu [State Key Laboratory on Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2014-08-28

    We report a high-performance colloidal quantum dot (CQD)-based near-infrared tandem photodetector fabricated on flexible substrates via solution-processed method. The tandem photodetector on poly(ethylene terephthalate) substrates exhibited low dark current and high detectivities over ?8.8?×?10{sup 11} Jones at near infrared range at ?0.5?V bias and over ?10{sup 13} Jones near 0 bias. The critical bend radii of ?8?mm and ?3?mm have been demonstrated for tensile and compressive bending, respectively. The performance of photodetectors remains stable under mechanical stress, making PbSe CQD material a promise candidate for flexible infrared sensing applications.

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

    SciTech Connect

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

    1994-06-01

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

  17. Pavement Design TTP Orientation Seminar

    E-print Network

    Handy, Susan L.

    Cycle · Infrastructure Life Cycle ­ Deployment ­ Maintenance ­ Rehabilitation ­ Reconstruction? and will this change? · Most pavements are made of engineered soils and processed rock · Asphalt concrete is 85

  18. Pavement Design TTP Orientation Seminar

    E-print Network

    Handy, Susan L.

    Cycle · Infrastructure Life Cycle ­Deployment ­Maintenance ­Rehabilitation ­Reconstruction (Abandonment? and will this change? · Most pavements are made of engineered soils and processed rock · Asphalt concrete is 85

  19. High Performance Fibers Based on Rigid and Flexible Polymers

    Microsoft Academic Search

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

    2008-01-01

    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

  20. High-Performance Concrete Carpet: A Hydraulic Flexible Wearing Course

    Microsoft Academic Search

    François de Larrard; Jean-Pierre Kerzrého; Jean-Marc Potier; Ludovic Baroin; Joseph Abdo

    2005-01-01

    This second paper presents two large-scale experiments dealing with the High-Performance Carpet. In the first one, a 10-m long slab was cast and monitored during one year; then a linear fatigue machine was brought on the model, and a series of one million of loading cycles was applied. The second trial was an experimental construction site, where a 120-m long

  1. Effect of flexibility of wing on aerodynamic performance in plunge motion

    NASA Astrophysics Data System (ADS)

    Le, Tuyen Quang; Ko, Jin Hwan; Park, Soo Hyung; Byun, Doyoung

    2009-11-01

    The improvement of aerodynamic performance in plunge motion is investigated through a flexibility of chordwise and spanwise directions by applied a prescribed deformation on a airfoil at Reynolds number of 30000. The aerodynamic performance of flapping motion can be evaluated through a thrust force, a input power and a propulsive efficiency which is a ratio of propulsive power which generate from thrust force to input power. Unsteady viscous flows over NACA 0012 airfoils in plunge motions are computed by using a time-accurate preconditioned Navier-Stokes solver coupled with a volume grid deformation code. For spanwise or chordwise flexibility, there is a optimal phase angle for maximum thrust force and propulsive efficiency. Especially, a combination of spanwise and chordwise flexibility can improve aerodynamic performance higher than that of adding increment from each of flexibility. Compared with rigid motion, 10% deformation in chordwise and spanwise directions with zero phase angle can enhance the thrust force coefficient from 0.22 to 0.38 and 0.54 respectively, while thrust force coefficient is 0.8 by combination of spanwise and chordwise flexibility.

  2. EXPERIMENTAL STUDY AND NUMERICAL ANALYSIS OF THE RUTTING PROBLEM OF AN ASPHALT PAVEMENT

    Microsoft Academic Search

    XU WEI; ZHANG XIAO-NING

    Premature rutting distress of a freeway in south China was systemically surveyed. The influence of rutting on the smoothness and roughness of pavement is analysed in this paper. A RLWT (Rotary Loaded Wheel Tester) was first used to analyse the pavement rutting performance. The anti-rutting performance of each course of asphalt concrete from different sections of rutting depth was appraised

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

    Microsoft Academic Search

    Hao Wang; Imad L. Al-Qadi

    2009-01-01

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

  4. Using finite element analysis of retroreflective raised pavement markers to recommend testing procedures for simulating their field performance

    E-print Network

    Agrawal, Ravi Prakash

    2006-08-16

    laboratory-testing procedures that could simulate the field performance of the RRPMs. Based on these simulations, the researcher recommended that the ASTM compression test for evaluation of RRPMs be continued or a similar test be developed. He suggested...

  5. Performance Improvement of a Flexible Telescope Through Metrology and Active Control

    Microsoft Academic Search

    Albert Greve; Hans JÜrgen Karcher

    2009-01-01

    A radio telescope is a flexible structure under the influence of gravity, temperature, and wind. Even after all passive means of telescope construction have been applied, the residual structural deformations of a high precision telescope may still lead to focus, pointing, and path-length errors and a loss in gain that exceed the performance specifications. Gravity-induced deformations can be calculated and

  6. Flexible and Modular Support for Timing Functions in High Performance Networking Acceleration

    Microsoft Academic Search

    Christopher E. Neely; Gordon J. Brebner; Weijia Shang

    2010-01-01

    Field programmable logic is increasingly used to provide the high performance and flexible acceleration needed for network processing functions at multiple gigabit\\/second rates. Almost all such functions feature the use of clocks and timers in control and\\/or data roles, and these are typically implemented in an ad hoc manner. This paper introduces a set of three configurable timing modules that

  7. Operational effectiveness and strategic flexibility: scales for performance assessment of new product development systems

    Microsoft Academic Search

    Weerd-Nederhof de Petra C; Klaasjan Visscher; Jelmer Altena; Olaf A. M. Fisscher

    2008-01-01

    Many firms attribute a central role to their New Product Development (NPD) function, in speeding up time to market, improving product quality, increasing manufacturing efficiency, building core competence and increasing innovative ability, often all within one and the same NPD system. This balancing of short-term operational effectiveness and longer-term strategic flexibility requires accurate insight in NPD performance on both dimensions.

  8. On the effect of flexibility on the performance of a bio-inspired fin

    NASA Astrophysics Data System (ADS)

    Chiazza, Stefano; Bremer, Florian H. J.; Smits, Alexander J.

    2013-11-01

    Experiments are performed to examine the flowfield characteristics of bio-inspired fins of different flexibility. The measurements are performed in a water channel at a fixed frequency of oscillation and different flow velocities covering the free-swimming condition. Thrust and efficiency measurements are complemented by PIV and flow visualizations studies. The wake topology is analyzed at different Strouhal numbers for each flexibility, and the differences between accelerating, decelerating, and free-swimming fins are identified. Experiments are performed to examine the flowfield characteristics of bio-inspired fins of different flexibility. The measurements are performed in a water channel at a fixed frequency of oscillation and different flow velocities covering the free-swimming condition. Thrust and efficiency measurements are complemented by PIV and flow visualizations studies. The wake topology is analyzed at different Strouhal numbers for each flexibility, and the differences between accelerating, decelerating, and free-swimming fins are identified. This work was supported by the ONR through MURI Grant N00014-08-1-0642 (Program Manager: Dr. Bob Brizzolara).

  9. Performance evaluation of a high durability asphalt binder and a high durability asphalt mixture for bridge deck pavements

    Microsoft Academic Search

    Hee Mun Park; Ji Young Choi; Hyun Jong Lee; Eui Yoon Hwang

    2009-01-01

    This paper describes the results of laboratory and full-scale performance tests for a high durability asphalt binder (HDAB) and high durability asphalt mixture (HDAM) applicable to the wearing course in a bridge deck system. The HDAB was developed using a styrene–butadiene–styrene (SBS) modifier and hydrocarbon for improving construction workability and resistance to fatigue cracking. Various binder tests were conducted on

  10. European Scanning Tour of PCC Pavements

    E-print Network

    Findings: Construction and Materials · Recycled concrete and recycled asphalt pavement used (or mandatedEuropean Scanning Tour of PCC Pavements June 27, 2007 E. Tom Cackler, P.E. National Concrete, and implementable in the US, for achieving longer concrete pavement service lives #12;7 of 33 Findings: Pavement

  11. A high-performance poly-Si TFT technology compatible with flexible plastic substrates

    Microsoft Academic Search

    Y.-J. Tung; P. M. Carey; P. M. Smith; S. D. Theiss; X. Meng; R. Weiss; G. A. Davis; V. Aebi; T.-J. King

    1998-01-01

    The development of a high-performance polycrystalline silicon (poly-Si) thin film transistor (TFT) technology which is compatible with plastic substrates is critical to the realisation of active matrix flat-panel displays that are flexible, lightweight, low cost and rugged. In this paper, we present performance comparisons of self-aligned aluminium top-gate poly-Si TFTs fabricated using a maximum substrate temperature of 150°C using excimer

  12. Design analysis of performance and aerodynamic loading of non-flexible horizontal-axis wind turbines

    Microsoft Academic Search

    R. E. Wilson; E. M. Patton

    1978-01-01

    The objective of this report is to develop simplified methods of determining the performance and aerodynamic loading of non-flexible horizontal-axis wind turbines. A general discussion and background of wind-turbine aerodynamics is given. Horizontal-axis wind-turbine performance in a uniform wind is covered. A calculation scheme is developed and exampes are given. The calculation scheme and program listing are given in detail.

  13. Assessing the Relative Rutting Susceptibility of HMA in the Laboratory with the Asphalt Pavement Analyzer

    Microsoft Academic Search

    N. M. Jackson; C. D. Baldwin

    2000-01-01

    The Strategic Highway Research Program (SHRP) identified rutting as a major cause of distress for Hot Mix Asphalt (HMA) pavements. The resulting Superior Performing Asphalt Pavements (Superpave) mix design system specifically addressed the aggregate and asphalt binder properties that contribute to permanent deformation. However, the Superpave system does not currently include a laboratory proof-test to quickly assess the rutting susceptibility

  14. Evaluation of Surface and Subsurface Processes in Permeable Pavement Infiltration Trenches

    EPA Science Inventory

    The hydrologic performance of permeable pavement systems can be affected by clogging of the pavement surface and/or clogging at the interface where the subsurface storage layer meets the underlying soil. As infiltration and exfiltration are the primary functional mechanisms for ...

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

    Microsoft Academic Search

    Yuan Xiao

    2009-01-01

    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

  16. Toward an Improved Model of Asphalt Binder Oxidation in Pavements

    E-print Network

    Prapaitrakul, Nikornpon

    2011-02-22

    Asphalt binder oxidation in pavements has been proven to be an ongoing process throughout a pavement's service life. Understanding the nature of the oxidation process is a critical step toward better pavement design to achieve greater pavement...

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

    PubMed Central

    Nakata, Toshiyuki; Liu, Hao

    2012-01-01

    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

  18. Flexible Electronics: Light Weight and Flexible High-Performance Diagnostic Platform (Adv. Healthcare Mater. 10/2015).

    PubMed

    Karnaushenko, Daniil; Ibarlucea, Bergoi; Lee, Sanghun; Lin, Gungun; Baraban, Larysa; Pregl, Sebastian; Melzer, Michael; Makarov, Denys; Weber, Walter M; Mikolajick, Thomas; Schmidt, Oliver G; Cuniberti, Gianaurelio

    2015-07-01

    A flexible light weight diagnostic platform is realized on cost-efficient large-area flexible foils enabling its cost-efficient high-volume delivery to medical institutions worldwide. The devices presented by L. Baraban, D. Makarov, and team on page 1517 allow the timely diagnosis of viral or infectious diseases, for example, the here demonstrated H1N1 subtype of the Avian Influenza Virus. PMID:26173420

  19. Airport pavement NDE research at CQEFP

    NASA Astrophysics Data System (ADS)

    Popovics, John S.; Achenbach, Jan D.

    1996-11-01

    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.

  20. Comparative performance of gold wire bonding on rigid and flexible substrates

    Microsoft Academic Search

    Yu Hin Chan; Jang-Kyo Kim; Deming Liu; Peter C. K. Liu; Yiu Ming Cheung; Ming Wai Ng

    2006-01-01

    This paper reports comparative performance of wire bondability of electrolytically plated Au\\/Ni\\/Cu bond pads on rigid FR-4\\u000a and bismaleimide trazine (BT) PCBs, as well as flexible polyimide (PI) substrate. The metallization surfaces were treated\\u000a with plasma to study the effect of bond pad surface cleanliness on wire bondability. Process windows were constructed as a\\u000a function of bonding temperature and bond

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

    NASA Technical Reports Server (NTRS)

    Whorton, M. S.

    1998-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Loizos, Andreas; Plati, Christina

    2014-05-01

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

  3. JOINT PERFORMANCE Guide for Optimum

    E-print Network

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

  4. Pervious Pavement System Evaluation- Abstract

    EPA Science Inventory

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

  5. Engineering Properties of Florida Concrete Mixes for Implementing the AASHTO Recommended Mechanistic-Empirical Rigid Pavement Design Guide

    Microsoft Academic Search

    Raphael Kampmann

    2008-01-01

    The coefficient of thermal expansion (CTE) is a fundamental property of Portland cement concrete (PCC). The magnitude of temperature-related pavement deformations is directly proportional to the CTE during the pavement design life. Because of its critical effect on PCC performance, it is proposed to be considered for distress and smoothness prediction by the newly developed Mechanistic-Empirical Pavement Design Guide (M-E

  6. Exact performance analytical model for spectrum allocation in flexible grid optical networks

    NASA Astrophysics Data System (ADS)

    Yu, Yiming; Zhang, Jie; Zhao, Yongli; Li, Hui; Ji, Yuefeng; Gu, Wanyi

    2014-03-01

    Dynamic flexible grid optical networks have gained much attention because of the advantages of high spectrum efficiency and flexibility, while the performance analysis will be more complex compared with fixed grid optical networks. An analytical Markov model is first presented in the paper, which can exactly describe the stochastic characteristics of the spectrum allocation in flexible grid optical networks considering both random-fit and first-fit resource assignment policies. We focus on the effect of spectrum contiguous constraint which has not been systematically studied in respect of mathematical modeling, and three major properties of the model are presented and analyzed. The model can expose key performance features and act as the foundation of modeling the Routing and Spectrum Assignment (RSA) problem with diverse topologies. Two heuristic algorithms are also proposed to make it more tractable. Finally, several key parameters, such as blocking probability, resource utilization rate and fragmentation rate are presented and computed, and the corresponding Monte Carlo simulation results match closely with analytical results, which prove the correctness of this mathematical model.

  7. Electronic performance of flexible single-wall carbon nanotube films: The role of electronic type

    NASA Astrophysics Data System (ADS)

    Harris, John M.; Hudson, Steven D.; Fagan, Jeffrey A.; Hobbie, Erik K.

    2012-02-01

    Recent advances in the separation of single-wall carbon nanotubes (SWCNTs) by length and electronic type have made highly monodisperse SWCNT membranes a reality, opening up new realms of potential application in flexible electronics. By measuring the coupling between mechanical flexibility and electronic performance for thin transparent films of metallic and semiconducting SWCNTs assembled on elastic polymer substrates, we demonstrate a marked difference in the electronic manifestations of thin-film deformation for the two electronic SWCNT types. We relate these differences to mechanical and interfacial phenomena that stem from the distinct optical resonances characteristic of metallic or semiconducting nanotubes, and we evaluate the durability of each film type in response to repeated mechanical strain.

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

    NASA Astrophysics Data System (ADS)

    Byrum, Christopher Ronald

    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.

  9. Asphalt Concrete Strain Responses at High Loads and Low Speeds At the National Airport Pavement Test Facility (NAPTF)

    Microsoft Academic Search

    Navneet Garg; Gordon F. Hayhoe

    Results are described from asphalt strain gage measurements made during pavement response tests on the flexible pavement test items at the National Airport Pavement Test Facility (NAPTF). Tests were run at speeds of 0.08, 0.15, 0.23, 0.3, 0.6, 1.5, and 2.2 m\\/sec (0.25, 0.5, 0.75, 1.0, 2.0, 5.0, and 7.33 feet\\/sec) with dual-wheel configurations at wheel loads of 106.8, 133.5,

  10. Asphalt Oxidation Kinetics and Pavement Oxidation Modeling 

    E-print Network

    Jin, Xin

    2012-07-16

    Most paved roads in the United States are surfaced with asphalt. These asphalt pavements suffer from fatigue cracking and thermal cracking, aggravated by the oxidation and hardening of asphalt. This negative impact of asphalt oxidation on pavement...

  11. Demonstration of Technologies for Concrete Pavement Quality

    E-print Network

    the National CP Tech Center The mission of the National Concrete Pavement Technology Center is to unite key transportation stakeholders around the central goal of advancing concrete pavement technology through research

  12. Study of flexible fin and compliant joint stiffness on propulsive performance: theory and experiments.

    PubMed

    Kancharala, A K; Philen, M K

    2014-09-01

    The caudal fin is a major source of thrust generation in fish locomotion. Along with the fin stiffness, the stiffness of the joint connecting the fish body to the tail plays a major role in the generation of thrust. This paper investigates the combined effect of fin and joint flexibility on propulsive performance using theoretical and experimental studies. For this study, fluid-structure interaction of the fin has been modeled using the 2D unsteady panel method coupled with nonlinear Euler-Bernoulli beam theory. The compliant joint has been modeled as a torsional spring at the leading edge of the fin. A comparison of self-propelled speed and efficiency with parameters such as heaving and pitching amplitude, oscillation frequency, flexibility of the fin and the compliant joint is reported. The model also predicts the optimized stiffnesses of the compliant joint and the fin for maximum efficiency. Experiments have been carried out to determine the effect of fin and joint stiffness on propulsive performance. Digital image correlation has been used to measure the deformation of the fins and the measured deformation is coupled with the hydrodynamic model to predict the performance. The predicted theoretical performance behavior closely matches the experimental values. PMID:24737004

  13. Fatigue properties of rubber modified pavements. Final report

    SciTech Connect

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

    1995-05-01

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

  14. Undergraduate Work Study Experience in Pavement Management

    Microsoft Academic Search

    Subhi M. Bazlamit; Farhad Reza

    Pavement management systems are used by many agencies as a tool for making informed decisions about pavements in the area of construction, design and maintenance. Since funds are limited, it is only possible, in many instances, to rehabilitate a limited number of pavement projects. Hence, the need for priority allocation of funds to projects and the appropriate timing of such

  15. Capturing Solar Energy from Asphalt Pavements

    Microsoft Academic Search

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

    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

  16. Summary of Concrete Overlays Existing concrete pavement

    E-print Network

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

  17. Making "Magic" Sidewalks of Pervious Pavement

    NSDL National Science Digital Library

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

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

  18. Use of Ground Penetrating Radar at the FAA's National Airport Pavement Test Facility

    NASA Astrophysics Data System (ADS)

    Injun, Song

    2015-04-01

    The Federal Aviation Administration (FAA) in the United States has used a ground-coupled Ground Penetrating Radar (GPR) at the National Airport Pavement Test Facility (NAPTF) since 2005. One of the primary objectives of the testing at the facility is to provide full-scale pavement response and failure information for use in airplane landing gear design and configuration studies. During the traffic testing at the facility, a GSSI GPR system was used to develop new procedures for monitoring Hot Mix Asphalt (HMA) pavement density changes that is directly related to pavement failure. After reviewing current setups for data acquisition software and procedures for identifying different pavement layers, dielectric constant and pavement thickness were selected as dominant parameters controlling HMA properties provided by GPR. A new methodology showing HMA density changes in terms of dielectric constant variations, called dielectric sweep test, was developed and applied in full-scale pavement test. The dielectric constant changes were successfully monitored with increasing airplane traffic numbers. The changes were compared to pavement performance data (permanent deformation). The measured dielectric constants based on the known HMA thicknesses were also compared with computed dielectric constants using an equation from ASTM D4748-98 Standard Test Method for Determining the Thickness of Bound Pavement Layers Using Short-Pulse Radar. Six inches diameter cylindrical cores were taken after construction and traffic testing for the HMA layer bulk specific gravity. The measured bulk specific gravity was also compared to monitor HMA density changes caused by aircraft traffic conditions. Additionally this presentation will review the applications of the FAA's ground-coupled GPR on embedded rebar identification in concrete pavement, sewer pipes in soil, and gage identifications in 3D plots.

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

    PubMed

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

    2013-03-11

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

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

    PubMed

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

    2013-08-14

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

  1. Modeling and performance evaluation of flexible manufacturing systems using Petri nets

    SciTech Connect

    Callotta, M.P.; Cimenez, C.; Tazza, M. [Eletrica e Informatica Industrial, Curitiba (Brazil)

    1996-12-31

    A timed Petri net approach is used to model resource allocation-utilization-release patterns for performance evaluation. First, simple resource utilization sequences are derived from a directed graph representing the process plan of parts. Second, the place-transitions sequences are connected introducing places whose marking models the resources needed to perform the manufacturing operation indicated in the process plan. Time is introduced as a permanence time of tokens at the place-transition sequence, modeling the utilization time of resources. The corresponding model leads to a simultaneous resource possession problem. Finally, flow equations for the description of the quantitative behavior of the resulting timed Petri net are presented. A major conclusion of the paper is that performance evaluation can be adequately abstracted and analytically solved, in a simple way, even in presence of complicating factors like resource sharing and routing flexibility in process plans.

  2. Improvement of the aerodynamic performance by wing flexibility and elytra–hind wing interaction of a beetle during forward flight

    PubMed Central

    Le, Tuyen Quang; Truong, Tien Van; Park, Soo Hyung; Quang Truong, Tri; Ko, Jin Hwan; Park, Hoon Cheol; Byun, Doyoung

    2013-01-01

    In this work, the aerodynamic performance of beetle wing in free-forward flight was explored by a three-dimensional computational fluid dynamics (CFDs) simulation with measured wing kinematics. It is shown from the CFD results that twist and camber variation, which represent the wing flexibility, are most important when determining the aerodynamic performance. Twisting wing significantly increased the mean lift and camber variation enhanced the mean thrust while the required power was lower than the case when neither was considered. Thus, in a comparison of the power economy among rigid, twisting and flexible models, the flexible model showed the best performance. When the positive effect of wing interaction was added to that of wing flexibility, we found that the elytron created enough lift to support its weight, and the total lift (48.4 mN) generated from the simulation exceeded the gravity force of the beetle (47.5 mN) during forward flight. PMID:23740486

  3. Measuring Clogging with Pressure Transducers in Permeable Pavement Strips

    EPA Science Inventory

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

  4. Monitoring Strategies in Permeable Pavement Systems to Optimize Maintenance Scheduling

    EPA Science Inventory

    As the surface in a permeable pavement system clogs and performance decreases, maintenance is required to preserve the design function. Currently, guidance is limited for scheduling maintenance on an as needed basis. Previous research has shown that surface clogging in a permea...

  5. SOURCE CONTROL FOR WATERSHED PROTECTION: PERMEABLE PAVEMENT TECHNOLOGY

    Microsoft Academic Search

    Elizabeth A. Fassman; Sam Blackbourn

    2007-01-01

    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

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

    PubMed

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

    2012-04-11

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

  7. Compaction Effects on Uniformity, Moisture Diffusion, and Mechanical Properties of Asphalt Pavements

    E-print Network

    Kassem, Emad Abdel-Rahman Ahmed

    2011-08-08

    Field compaction of asphalt mixtures is an important process that influences performance of asphalt pavements; however there is very little effort devoted to evaluate the influence of compaction on the uniformity and properties of asphalt mixtures...

  8. 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...

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

    SciTech Connect

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

    2012-02-09

    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.

  10. Performance testing of the 5 kW EOS AM-1 flexible solar array blanket

    SciTech Connect

    Schurig, H.H.; Kruer, M.A.; Levesque, M.N. [TRW Space and Electronics Group, Redondo Beach, CA (United States); Gaddy, E.M. [NASA/Goddard Space Flight Center, Greenbelt, MD (United States); Andiario, W.J. [Lockheed Martin Missiles and Space, Valley Forge, PA (United States)

    1997-12-31

    A GaAs/Ge flexible solar array blanket has been developed for use on the NASA/GSFC remote sensing EOS AM-1 spacecraft. This single wing array has been designed to provide a 5 kW of power after five years in a low earth polar orbit. The blanket configuration includes design features such as thin GaAs/Ge cell stacks mounted on a large flexible, hinged substrate, parallel connected solar cell strings providing high voltage output, a printed circuit harness, and a multi-layer jumper bus providing electrical continuity between the cell strings and the printed circuit harness. This work was contracted to TRW Space and Electronics Group in 1993 by Lockheed Martin Missiles and Space (LMMS). This paper presents the essential design of the EOS AM-1 solar array blanket, and summarizes the results of a qualification test program designed to demonstrate adequate design margins and to assess the performance of the mechanical and electrical components after exposure to a simulated mission space environment. It also reviews the complexities of performing electrical output on a 8.9 m x 5.0 m deployed solar array blanket under AM0 conditions.

  11. Scalable fabrication of high-performance and flexible graphene strain sensors

    NASA Astrophysics Data System (ADS)

    Tian, He; Shu, Yi; Cui, Ya-Long; Mi, Wen-Tian; Yang, Yi; Xie, Dan; Ren, Tian-Ling

    2013-12-01

    Graphene strain sensors have promising prospects of applications in detecting human motion. However, the shortage of graphene growth and patterning techniques has become a challenging issue hindering the application of graphene strain sensors. Therefore, we propose wafer-scale flexible strain sensors with high-performance, which can be fabricated in one-step laser scribing. The graphene films could be obtained by directly reducing graphene oxide film in a Light-Scribe DVD burner. The gauge factor (GF) of the graphene strain sensor (10 mm × 10 mm square) is 0.11. In order to enhance the GF further, graphene micro-ribbons (20 ?m width, 0.6 mm long) has been used as strain sensors, of which the GF is up to 9.49. The devices may conform to various application requirements, such as high GF for low-strain applications and low GF for high deformation applications. The work indicates that laser scribed flexible graphene strain sensors could be widely used in medical-sensing, bio-sensing, artificial skin and many other areas.Graphene strain sensors have promising prospects of applications in detecting human motion. However, the shortage of graphene growth and patterning techniques has become a challenging issue hindering the application of graphene strain sensors. Therefore, we propose wafer-scale flexible strain sensors with high-performance, which can be fabricated in one-step laser scribing. The graphene films could be obtained by directly reducing graphene oxide film in a Light-Scribe DVD burner. The gauge factor (GF) of the graphene strain sensor (10 mm × 10 mm square) is 0.11. In order to enhance the GF further, graphene micro-ribbons (20 ?m width, 0.6 mm long) has been used as strain sensors, of which the GF is up to 9.49. The devices may conform to various application requirements, such as high GF for low-strain applications and low GF for high deformation applications. The work indicates that laser scribed flexible graphene strain sensors could be widely used in medical-sensing, bio-sensing, artificial skin and many other areas. Electronic supplementary information (ESI) available: Testing results and discussion of graphene strain sensors. See DOI: 10.1039/c3nr04521h

  12. The impact of maintenance and rehabilitation strategies on the pavement network value 

    E-print Network

    Chang Albitres, Carlos Martin

    1999-01-01

    Effectiveness Due to a Given Scenario. . . 55 13 Area under the Pavement Performance Curve for a Do Nothing Scenario . . . . . . . 56 14 Area under the Performance Curve for a Given Scenario . . . . . . . . . 57 15 Effectiveness for a Given Scenario. . 58 16... Period for Different Scenarios. . . 66 21 AUAC/RL versus PCI at the End of the Analysis Period for Different Scenarios . . 66 Normalized Scenario Cost Effectiveness Ratio (NSCER) for Different Scenarios . 67 23 A Typical Definition of Pavement...

  13. Research progress and prospect of application technology of thin-layer antiskid colored pavement at home and abroad

    Microsoft Academic Search

    Liu Hengquan; Zhang Zhiyong; Guo Donghua; Peng Lei; Bao Zuojun; Han Wenyuan

    2011-01-01

    The particularity of driving environment and antiskid performance of pavement are important factors which influence traffic safety at some particular road sections such as entrances and exits of tunnels, continuous curves, large longitudinal slopes and toll- gates. In recent years, a kind of thin-layer antiskid colored pavement has been widely used at these particular road sections, which plays an important

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

    Microsoft Academic Search

    Zongzhi Li; Kumares C. Sinha

    2000-01-01

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

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

    Microsoft Academic Search

    Liu Lijun; Zhang Hui

    2010-01-01

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

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

    PubMed

    Kadurupokune, N; Jayasuriya, N

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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.

  18. The evaluation of airfield pavements 

    E-print Network

    Poor, Arthur Reginald

    1960-01-01

    future needs may be determined, c. Determine the existing strength of a pavement complex and whether reinforcement is required. d. . provide an economic tool in planning for future oonstruc- tion to avoid "crash" replacement programs. e, Serve as a... and actual life of airfield pavements, some theoretical and some practical. However, 9 Tersaghi, Karl and Peck, HgQ. ph B. , ~o . cit. , p. 107. 10 Glidden, H. K?Law, H. F?and Cowles, J. E, , ~rr&overt, McGraw- Hill Book Co? New York, 19l+6, p . 111...

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

    E-print Network

    Pavement Smoothness for Illinois DOT - Doug Dirks 1. Briefly summarize your current pavement? N/A Illinois has both standard specifications and a special provision for pavement smoothness-Depth HMA Pavement 407.09 PCC Pavement 420.10 The following is a link to Division 400 of the Illinois

  20. High performance solid state flexible supercapacitor based on molybdenum sulfide hierarchical nanospheres

    NASA Astrophysics Data System (ADS)

    Javed, Muhammad Sufyan; Dai, Shuge; Wang, Mingjun; Guo, Donglin; Chen, Lin; Wang, Xue; Hu, Chenguo; Xi, Yi

    2015-07-01

    Molybdenum sulfide (MoS2) hierarchical nanospheres are synthesized using a hydrothermal method and characterized by X-ray powder diffraction, Brunauer-Emmett-Teller, scanning electron microscopy and transmission electron microscopy. The prepared MoS2 is used to fabricate solid state flexible supercapacitors which show excellent electrochemical performance such as high capacitance 368 F g-1 at a scan rate of 5 mV s-1 and high power density of 128 W kg-1 at energy density of 5.42 Wh kg-1. The fabricated supercapacitor presents good characteristics such as lightweight, low cast, portability, high flexibility, and long term cycling stability by retaining 96.5% after 5000 cycles at constant discharge current of 0.8 mA. Electrochemical impedance spectroscopy (EIS) results reveal low resistance and suggest that MoS2 nanospheres would be a promising candidate for supercapacitors. Three charged supercapacitors connected in series can light 8 red color commercial light emitting diodes (LEDs) for 2 min, demonstrating its capability as a good storage device.

  1. PLATT: a flexible platform for experimental research on team performance in complex environments.

    PubMed

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

    2010-08-01

    The present article introduces PLATT, a recently developed task environment for controlled experimental research on team performance in complex environments. PLATT was developed to meet the research demands posed by the complexity that present-day teams face. It consists of a flexible, modular software architecture and research-specific scenarios. The scenarios can target various types of tasks (e.g., planning, problem solving, and decision making) in different operational contexts. Different software configurations can be used to investigate questions pertaining to team structure, team virtuality, and multiteam systems. We describe the software architecture, one of the scenarios, and the broad range of automated and embedded measurement possibilities that PLATT offers. To illustrate PLATT's possibilities, in the present article, we describe a number of experiments that have used PLATT for a variety of research questions. We conclude that PLATT meets the formulated research demands and provides researchers with a flexible platform to investigate the complex issues that present-day teams face. PMID:20805596

  2. Scalable fabrication of high-performance and flexible graphene strain sensors.

    PubMed

    Tian, He; Shu, Yi; Cui, Ya-Long; Mi, Wen-Tian; Yang, Yi; Xie, Dan; Ren, Tian-Ling

    2014-01-21

    Graphene strain sensors have promising prospects of applications in detecting human motion. However, the shortage of graphene growth and patterning techniques has become a challenging issue hindering the application of graphene strain sensors. Therefore, we propose wafer-scale flexible strain sensors with high-performance, which can be fabricated in one-step laser scribing. The graphene films could be obtained by directly reducing graphene oxide film in a Light-Scribe DVD burner. The gauge factor (GF) of the graphene strain sensor (10 mm × 10 mm square) is 0.11. In order to enhance the GF further, graphene micro-ribbons (20 ?m width, 0.6 mm long) has been used as strain sensors, of which the GF is up to 9.49. The devices may conform to various application requirements, such as high GF for low-strain applications and low GF for high deformation applications. The work indicates that laser scribed flexible graphene strain sensors could be widely used in medical-sensing, bio-sensing, artificial skin and many other areas. PMID:24281713

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

    PubMed

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

    2013-10-28

    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

  4. Bituminous pavement recycling Aravind K. and Animesh Das

    E-print Network

    Das, Animesh

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

  5. Toward an Improved Model of Asphalt Binder Oxidation in Pavements 

    E-print Network

    Prapaitrakul, Nikornpon

    2011-02-22

    the percentage of accessible air voids in the pavement is considerably lower (2 percent or less), the hardening rate of binders in pavements is reduced significantly. Field evidence is mounting that asphalt binder oxidization in pavements produces a binder...

  6. Concrete Pavement Surface Characteristics Program

    E-print Network

    Concrete Pavement Surface Characteristics Program Site Evaluation Report Site 211-1 (Pre- and Post- Grinding/Grooving, Pre-Traffic) Site 211-2 (Post-Traffic, 1 week) Two-Lift Concrete Paving Demonstration, near Solomon, Kansas Two-Lift Concrete Paving Demonstration Project Surface A, Longitudinal Tining

  7. Pavement Design TTP Orientation Seminar

    E-print Network

    Handy, Susan L.

    · Builder · Society ­Internal ­External #12;Pavement Life Cycle · Infrastructure Life Cycle ­Deployment soils and processed rock · Asphalt concrete is 85% aggregate by volume; 10% asphalt; some plastic on product life cycle and waste ­ Pneumatic tire loads and inflation pressures ­ Operating speeds

  8. Effect of Lumbar Spine Manipulation on Asymptomatic Cyclist Sprint Performance and Hip Flexibility

    PubMed Central

    Olson, Eric; Bodziony, Michael; Ward, John; Coats, Jesse; Koby, Bradley; Goehry, Doug

    2014-01-01

    Objective The purpose of this study was to measure the impact of midlumbar spinal manipulation on asymptomatic cyclist sprint performance and hip flexibility. Methods Twelve cyclists were equally randomized into an AB:BA crossover study design after baseline testing. Six participants were in the AB group, and 6 were in the BA group. The study involved 1 week of rest in between each of the 3 tested conditions: baseline testing (no intervention prior to testing), condition A (bilateral midlumbar spine manipulation prior to testing), and condition B (sham acupuncture prior to testing, as a control). Testing was blinded and involved a sit-and-reach test followed by a 0.5-km cycle ergometer sprint test against 4-kp resistance. Outcome measures were sit-and-reach distance, time to complete 0.5 km, maximum heart rate, and rating of perceived exertion. An additional 8 cyclists were recruited and used as a second set of controls that engaged in 3 testing sessions without any intervention to track test acclimation. An analysis of variance was used to compare dependent variables under each of the 3 conditions for the experimental group and control group #1, and a repeated-measures analysis of variance was used to analyze test acclimation in control group #2. Results Lumbar spine manipulation did not demonstrate statistically significant between-group changes in sit-and-reach (P = .765), 0.5-km sprint performance time (P = .877), maximum exercise heart rate (P = .944), or rating of perceived exertion (P = .875). Conclusions The findings of this preliminary study showed that midlumbar spinal manipulation did not improve hip flexibility or cyclist power output of asymptomatic participants compared with an acupuncture sham and no-treatment control groups. PMID:25435836

  9. Indications for performing flexible bronchoscopy: Trends over 34 years at a tertiary care hospital

    PubMed Central

    Gupta, Ankit Amar; Sehgal, Inderpaul Singh; Dhooria, Sahajal; Singh, Navneet; Aggarwal, Ashutosh Nath; Gupta, Dheeraj; Behera, Digambar; Agarwal, Ritesh

    2015-01-01

    Background and Aim: Due to its easy maneuverability, patient comfort and documented safety as an outpatient procedure, flexible bronchoscopy (FB) has replaced rigid bronchoscopy for routine diagnostic use. Herein, we report our 34-year experience with outpatient performance of FB. Materials and Methods: This was a retrospective analysis of all FB procedures performed between September 1979 and November 2013 (period I: 1979-1990; period II: 1991-2000; period III: 2001-2013) in a tertiary care hospital. Demographic profile of patients, indications for performing FB, and annual and seasonal trends were noted from the records. Results: A total of 24,814 bronchoscopies were performed during the study period. The mean (SD) age of patients (71.6% males) was 48.4 (15.5) years. The number of procedures performed per decade showed an absolute increase by 322%. The most common indication for FB was suspected bronchogenic carcinoma (32.2%) followed by pulmonary infections (18.6%) and interstitial lung diseases (13%). The proportion of annual cases due to interstitial lung diseases (3.9% in period I to 16.2% in period III) increased over the years, whereas disorders such as hemoptysis and pleural effusion showed a declining trend as an indication for FB. A seasonal trend was observed for diseases such as sarcoidosis, bronchogenic carcinoma and pulmonary infections. Six deaths were encountered during the study period in patients undergoing FB. Conclusion: FB is increasingly being performed in the diagnosis of respiratory disorders and is a safe outpatient procedure. Although bronchogenic carcinoma remains a common indication for performing FB, benign conditions such as pulmonary infections and sarcoidosis constitute important indications in the Indian scenario. PMID:25983404

  10. Exploring pavement crack evaluation with bidimensional empirical mode decomposition

    NASA Astrophysics Data System (ADS)

    Ayenu-Prah, Albert; Attoh-Okine, Nii

    2007-04-01

    Crack evaluation is essential for effective classification of pavement cracks. Digital images of pavement cracks have been analyzed using techniques such as fuzzy set theory and neural networks. Bidimensional empirical mode decomposition (BEMD), a new image analysis method recently developed, can potentially be used for pavement crack evaluation. BEMD is an extension of the empirical mode decomposition (EMD), which can decompose non-linear and non-stationary signals into basis functions called intrinsic mode functions (IMF). IMFs are monocomponent functions that have well defined instantaneous frequencies. EMD is a sifting process that is non-parametric and data-driven; it does not depend on an a priori basis set. It is able to remove noise from signals without complicated convolution processes. BEMD decomposes an image into two-dimensional IMFs. The present paper explores pavement crack detection using BEMD together with the Sobel edge detector. A number of images are filtered with BEMD to remove noise, and the residual image analyzed with the Sobel edge detector for crack detection. The results are compared with results from the Canny edge detector, which uses a Gaussian filter for image smoothing before performing edge detection. The objective is to qualitatively explore how well BEMD is able to smooth an image for more effective and speedier edge detection with the Sobel method.

  11. PAVEMENT RESPONSES AT ASPHALT SURFACE UNDER MEASURED 3-D TIRE-PAVEMENT CONTACT STRESSES

    Microsoft Academic Search

    Rong Luo; Jorge A. Prozzi

    Pavement design methods assume that the tire-pavement contact stress is equal to the tire inflation pressure and is uniformly distributed in the vertical direction over the contact area. However, because of these assumptions, this uniform stress model does not correctly estimate pavement surface strains, which are used to determine the top-down fatigue cracking. To precisely account for the actual contact

  12. Effect of vehicle–pavement interaction on dynamic response of rigid pavements

    Microsoft Academic Search

    V. A. Sawant; V. A. Patil; Kousik Deb

    2011-01-01

    In the present paper, dynamic response of rigid pavements subjected to moving vehicular loads is presented using an analytical procedure based on the finite element method. The vehicle–pavement interaction effects are taken into account while developing the solution algorithm. The concrete pavement is discretized by finite and infinite beam elements. Infinite elements are helpful in appropriate modeling of end conditions.

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

    Microsoft Academic Search

    M. Mustaffar; T. C. Ling

    1998-01-01

    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

  14. Enhanced electrochemical performance of polyaniline/carbon/titanium nitride nanowire array for flexible supercapacitor

    NASA Astrophysics Data System (ADS)

    Xie, Yibing; Xia, Chi; Du, Hongxiu; Wang, Wei

    2015-07-01

    The ternary nanocomposite of polyaniline/carbon/titanium nitride (PANI/C/TiN) nanowire array (NWA) is fabricated as electroactive electrode material for flexible supercapacitor application. Firstly, TiN NWA is formed through ammonia nitridation treatment of TiO2 NWA, which is synthesized via seed-assisted hydrothermal reaction. PANI/C/TiN NWA is then formed through sequentially coating carbon and PANI on the surface of TiN NWA. PANI/C/TiN NWA has unique shell/shell/core architecture, including a core layer of TiN NWA with a diameter of 40-160 nm and a length of 1.5 ?m, a middle shell layer of carbon with a thickness of about 6.0 nm and an external surface layer of PANI with a thickness of 20-50 nm. PANI/C/TiN NWA provides ion diffusion channel at interspaces between the neighboring nanowires and electron transfer route along independent nanowires. The carbon shell layer is able to protect TiN NWA from electrochemical corrosion during charge/discharge process. PANI/C/TiN NWA displays high specific capacitance of 1093 F g-1 at 1.0 Ag-1, and good cycling stability with a capacity retention of 98% after 2000 cycles, presenting better supercapacitive performance than other integrated nanocomposites of C/PANI/TiN, PANI/TiN and PANI/C/TiO2 NWA. Such a ternary nanocomposite of PANI/C/TiN NWA can be used as an electrode material of flexible supercapacitors.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  16. Recycling of water-susceptible pavements

    NASA Astrophysics Data System (ADS)

    Maupin, G. W.

    1980-05-01

    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.

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

    SciTech Connect

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

    2001-11-21

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

  18. Generation mechanisms of tire-pavement noise

    NASA Astrophysics Data System (ADS)

    Dare, Tyler P.

    Tire-pavement noise is the dominant source of traffic noise at highway speeds. It is the result of a combination of several noise generation mechanisms, including tire carcass vibration and tread block vibration. Because multiple mechanisms are involved, it is difficult to predict the effects of changes in pavement parameters on tire-pavement noise. In this research, a set of experimental techniques were developed to decompose a measured tire-pavement noise spectrum into a set of constituent spectra relating to each generation mechanism. Three principal mechanisms were identified: treadband vibration, sidewall vibration, and tangential tread block vibration. By combining the constituent spectra associated with these mechanisms, it was possible to accurately predict the total tire-pavement noise spectrum. The constituent spectra were fit to tire-pavement noise data measured on asphalt and concrete pavements at highway speeds. It was found that the constituent spectra fit the measured data well, and a two-parameter model was developed to predict tire-pavement noise levels from pavement texture data.

  19. A Flexible, High Performance Service-Oriented Architecture for Detecting Cyber Attacks

    SciTech Connect

    Wynne, Adam S.; Gorton, Ian; Almquist, Justin P.; Chatterton, Jack; Thurman, David A.

    2008-02-01

    The next generation of intrusion detection and cyber defense technologies must be highly flexible so that deployed solutions can be quickly modified to detect new attack scenarios. They must also be able to provide the performance necessary to monitor traffic from high speed networks, and scale to enterprise wide deployments. In this paper we describe our experiences in creating a production application for cyber situational awareness. The application exploits the capabilities of several independently developed components and integrates them using SIFT (Scalable Information Fusion and Triage), a service-oriented architecture (SOA) designed for creating domain-independent, enterprise scale analytical applications. SIFT exploits a common design pattern for composing analytical components, and extends an existing messaging platform with scaling capabilities. We describe the design of the application, and provide a performance analysis that demonstrates the capabilities of the SIFT platform. The paper concludes by discussing the lessons we have learned from this project, and outlines the architecture of the MeDICI, the next generation of our enterprise analytics platforms.

  20. Printable nanostructured silicon solar cells for high-performance, large-area flexible photovoltaics.

    PubMed

    Lee, Sung-Min; Biswas, Roshni; Li, Weigu; Kang, Dongseok; Chan, Lesley; Yoon, Jongseung

    2014-10-28

    Nanostructured forms of crystalline silicon represent an attractive materials building block for photovoltaics due to their potential benefits to significantly reduce the consumption of active materials, relax the requirement of materials purity for high performance, and hence achieve greatly improved levelized cost of energy. Despite successful demonstrations for their concepts over the past decade, however, the practical application of nanostructured silicon solar cells for large-scale implementation has been hampered by many existing challenges associated with the consumption of the entire wafer or expensive source materials, difficulties to precisely control materials properties and doping characteristics, or restrictions on substrate materials and scalability. Here we present a highly integrable materials platform of nanostructured silicon solar cells that can overcome these limitations. Ultrathin silicon solar microcells integrated with engineered photonic nanostructures are fabricated directly from wafer-based source materials in configurations that can lower the materials cost and can be compatible with deterministic assembly procedures to allow programmable, large-scale distribution, unlimited choices of module substrates, as well as lightweight, mechanically compliant constructions. Systematic studies on optical and electrical properties, photovoltaic performance in experiments, as well as numerical modeling elucidate important design rules for nanoscale photon management with ultrathin, nanostructured silicon solar cells and their interconnected, mechanically flexible modules, where we demonstrate 12.4% solar-to-electric energy conversion efficiency for printed ultrathin (? 8 ?m) nanostructured silicon solar cells when configured with near-optimal designs of rear-surface nanoposts, antireflection coating, and back-surface reflector. PMID:25272244

  1. High-performance flexible photodetectors based on GaTe nanosheets.

    PubMed

    Wang, Zhenxing; Safdar, Muhammad; Mirza, Misbah; Xu, Kai; Wang, Qisheng; Huang, Yun; Wang, Fengmei; Zhan, Xueying; He, Jun

    2015-04-28

    2D layered GaTe materials have attracted a great deal of attention for optoelectronic applications due to their direct band structure, whether in bulk or as a single layer. In this paper, for the first time, we have synthesized high quality, single crystalline GaTe nanosheets by employing a facile CVD method. The size of the GaTe nanosheets reached several tens of micrometers, and some of them even exceeded 100 ?m. In particular, planar GaTe nanosheets were achieved on a mica substrate following a van der Waals epitaxial growth mechanism. Further, through a systematic comparison of the performances under various conditions, we found that adsorbates on the GaTe surface under ambient conditions strongly deteriorated the GaTe photodetector device performance. After removing the adsorbates in a ? 7 × 10(-5) torr vacuum, a flexible, fast response GaTe photodetector with a high photoresponse, high mechanical stability and an excellent linear input-output relationship was obtained. The results presented in this study suggest that the GaTe nanosheets grown by a CVD method are promising candidates for optoelectronic applications in the future. PMID:25811647

  2. A modified analytical model to study the sensing performance of a flexible capacitive tactile sensor array

    NASA Astrophysics Data System (ADS)

    Liang, Guanhao; Wang, Yancheng; Mei, Deqing; Xi, Kailun; Chen, Zichen

    2015-03-01

    This paper presents a modified analytical model to study the sensing performance of a flexible capacitive tactile sensor array, which utilizes solid polydimethylsiloxane (PDMS) film as the dielectric layer. To predict the deformation of the sensing unit and capacitance changes, each sensing unit is simplified into a three-layer plate structure and divided into central, edge and corner regions. The plate structure and the three regions are studied by the general and modified models, respectively. For experimental validation, the capacitive tactile sensor array with 8? × ?8 (= 64) sensing units is fabricated. Experiments are conducted by measuring the capacitance changes versus applied external forces and compared with the general and modified models’ predictions. For the developed tactile sensor array, the sensitivity predicted by the modified analytical model is 1.25%/N, only 0.8% discrepancy from the experimental measurement. Results demonstrate that the modified analytical model can accurately predict the sensing performance of the sensor array and could be utilized for model-based optimal capacitive tactile sensor array design.

  3. High-performance flexible photodetectors based on GaTe nanosheets

    NASA Astrophysics Data System (ADS)

    Wang, Zhenxing; Safdar, Muhammad; Mirza, Misbah; Xu, Kai; Wang, Qisheng; Huang, Yun; Wang, Fengmei; Zhan, Xueying; He, Jun

    2015-04-01

    2D layered GaTe materials have attracted a great deal of attention for optoelectronic applications due to their direct band structure, whether in bulk or as a single layer. In this paper, for the first time, we have synthesized high quality, single crystalline GaTe nanosheets by employing a facile CVD method. The size of the GaTe nanosheets reached several tens of micrometers, and some of them even exceeded 100 ?m. In particular, planar GaTe nanosheets were achieved on a mica substrate following a van der Waals epitaxial growth mechanism. Further, through a systematic comparison of the performances under various conditions, we found that adsorbates on the GaTe surface under ambient conditions strongly deteriorated the GaTe photodetector device performance. After removing the adsorbates in a ~7 × 10-5 torr vacuum, a flexible, fast response GaTe photodetector with a high photoresponse, high mechanical stability and an excellent linear input-output relationship was obtained. The results presented in this study suggest that the GaTe nanosheets grown by a CVD method are promising candidates for optoelectronic applications in the future.

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

    PubMed

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

    2010-10-01

    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

  5. Application of flexible printed circuit board (FPCB) in personal computer motherboards: Focusing on Mechanical Performance

    Microsoft Academic Search

    W. C. Leong; M. Z. Abdullah; C. Y. Khor

    Flexible printed circuit boards (FPCBs) are being used extensively in current electronics devices because of their excellent flexibility, light weight, and reduced thickness. In the present study, a proposed novel approach that utilizes FPCB as a substrate for motherboards is investigated. Deflection and stress are the key factors that determine the feasibility of FPCB motherboards. As flow velocity increases, flow-induced

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

    NASA Astrophysics Data System (ADS)

    Kou, Nannan

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

  7. Improved performance of flexible amorphous silicon solar cells with silver nanowires

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    PubMed

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

    2012-08-01

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

  9. Roll-to-Roll Encapsulation of Metal Nanowires between Graphene and Plastic Substrate for High-Performance Flexible Transparent Electrodes.

    PubMed

    Deng, Bing; Hsu, Po-Chun; Chen, Guanchu; Chandrashekar, B N; Liao, Lei; Ayitimuda, Zhawulie; Wu, Jinxiong; Guo, Yunfan; Lin, Li; Zhou, Yu; Aisijiang, Mahaya; Xie, Qin; Cui, Yi; Liu, Zhongfan; Peng, Hailin

    2015-06-10

    Transparent conductive film on plastic substrate is a critical component in low-cost, flexible, and lightweight optoelectronics. Industrial-scale manufacturing of high-performance transparent conductive flexible plastic is needed to enable wide-ranging applications. Here, we demonstrate a continuous roll-to-roll (R2R) production of transparent conductive flexible plastic based on a metal nanowire network fully encapsulated between graphene monolayer and plastic substrate. Large-area graphene film grown on Cu foil via a R2R chemical vapor deposition process was hot-laminated onto nanowires precoated EVA/PET film, followed by a R2R electrochemical delamination that preserves the Cu foil for reuse. The encapsulated structure minimized the resistance of both wire-to-wire junctions and graphene grain boundaries and strengthened adhesion of nanowires and graphene to plastic substrate, resulting in superior optoelectronic properties (sheet resistance of ?8 ? sq(-1) at 94% transmittance), remarkable corrosion resistance, and excellent mechanical flexibility. With these advantages, long-cycle life flexible electrochromic devices are demonstrated, showing up to 10000 cycles. PMID:26020567

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

    PubMed

    Liu, Xiaoyu; Cui, Qingbin; Schwartz, Charles

    2014-01-01

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

  11. TECHNOLOGY FOR QUALITY ASSURANCE OF NEW PAVEMENT THICKNESS

    Microsoft Academic Search

    Kenneth R. Maser; Joseph Holland; Roger Roberts

    Accurate measurement of pavement thickness is an essential aspect of the quality assurance of new pavement construction. Current methods involving the use of cores are time consuming and provide a very limited representation of the overall pavement structure. The overall objective of the work described in this paper was to rapidly determine the average pavement thickness on a newly constructed

  12. Highway pavement distress evaluation: Modeling measurement error

    Microsoft Academic Search

    Frannie Humplick

    1992-01-01

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

  13. Reducing traffic noise with quieter pavements

    Microsoft Academic Search

    Paul Donavan

    2005-01-01

    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,

  14. Research on cracking control for FRAC pavement

    Microsoft Academic Search

    Yazhen Sun; Jiemin Liu; Tianqing Yu

    2010-01-01

    In this paper, relax moduli for FRAC(FRAC) is studied. Using Sidoroff damage model for concrete, viscoelastic damage parameters are determined in order to evaluate the cracking control of FRAC pavement. The results obtained from the coupling analysis of using linear elastic damage mechanics and elastic fracture mechanics simultaneously show that the relaxation damage factor of FRAC pavement is reduced by

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

    PubMed

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

    2013-01-11

    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

  16. Performance testing of the 5 kW EOS AM1 flexible solar array blanket

    Microsoft Academic Search

    H. H. Schurig; M. A. Kruer; M. N. Levesque; E. M. Gaddy; W. J. Andiario

    1997-01-01

    A GaAs\\/Ge flexible solar array blanket has been developed for use on the NASA\\/GSFC remote sensing EOS AM-1 spacecraft. This single wing array has been designed to provide 5 kW of power after five years in a low Earth polar orbit. The blanket configuration includes design features such as thin GaAs\\/Ge cell stacks mounted on a large flexible, hinged substrate,

  17. High-performance flexible perovskite solar cells exploiting Zn2SnO4 prepared in solution below 100?°C.

    PubMed

    Shin, Seong Sik; Yang, Woon Seok; Noh, Jun Hong; Suk, Jae Ho; Jeon, Nam Joong; Park, Jong Hoon; Kim, Ju Seong; Seong, Won Mo; Seok, Sang Il

    2015-01-01

    Fabricating inorganic-organic hybrid perovskite solar cells (PSCs) on plastic substrates broadens their scope for implementation in real systems by imparting portability, conformability and allowing high-throughput production, which is necessary for lowering costs. Here we report a new route to prepare highly dispersed Zn2SnO4 (ZSO) nanoparticles at low-temperature (<100?°C) for the development of high-performance flexible PSCs. The introduction of the ZSO film significantly improves transmittance of flexible polyethylene naphthalate/indium-doped tin oxide (PEN/ITO)-coated substrate from ?75 to ?90% over the entire range of wavelengths. The best performing flexible PSC, based on the ZSO and CH3NH3PbI3 layer, exhibits steady-state power conversion efficiency (PCE) of 14.85% under AM 1.5G 100?mW·cm(-2) illumination. This renders ZSO a promising candidate as electron-conducting electrode for the highly efficient flexible PSC applications. PMID:26096202

  18. Full scale demonstration of air-purifying pavement.

    PubMed

    Ballari, M M; Brouwers, H J H

    2013-06-15

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

  19. State-of-the-art review of the applications of nanotechnology in pavement materials

    NASA Astrophysics Data System (ADS)

    Castillo, Luis, Jr.

    The use of nanotechnology in pavement materials is one main area that shows great promise and has the potential to change commonly used materials. This will develop more effective solutions to achieve the desired performance. The overall objective of this work is to present a state-of-the-art literature review of nano-science-based principles to improve the performance and, ultimately, the life cycle of transportation construction materials. This work will be organized into two different parts. The first part will consist of six sections: applications of nanotechnology in concrete pavements, applications of nanotechnology in asphalt pavement, application of nanotechnology in general soils, cost-benefit analysis, challenges, and trends to the future. In addition, a current practice review was performed from a literature review that included a questionnaire of the knowledge and opinion about nanotechnology, which included students, general contractors, teachers, engineers, and architects. The second part will deal with the advancement of the application of nanotechnology in pavement materials for different developed countries. Because nanotechnology is relatively a young field in pavement materials, limited research has been conducted in North America, Europe, and Asia. A comparison of the advancement of nano-science-based principles, as applied to the performance and life cycle of transportation materials, for the three continents will be carried out in a summarized manner.

  20. 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...

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

    Microsoft Academic Search

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

    2010-01-01

    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

  2. Effective flow resistivity of highway pavements.

    PubMed

    Rochat, Judith L; Read, David R

    2013-12-01

    In the case of highway traffic noise, propagating sound is influenced by the ground over which it travels, whether it is the pavement itself or the ground between the highway and nearby communities. Properly accounting for ground type in modeling can increase accuracy in noise impact determinations and noise abatement design. Pavement-specific effective flow resistivity values are being investigated for inclusion in the Federal Highway Administration Traffic Noise Model, which uses these values in the sound propagation algorithms and currently applies a single effective flow resistivity value to all pavement. Pavement-specific effective flow resistivity values were obtained by applying a modified version of the American National Standards Institute S1.18 standard. The data analysis process was tailored to allow for increased sensitivity and extraction of effective flow resistivity values for a broad range of pavements (sound absorptive to reflective). For porous pavements (sound absorptive), it was determined that examination of the measured data can reveal influence from an underlying structure. Use of such techniques can aid in the design of quieter pavements. PMID:25669283

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

    E-print Network

    Han, Rongbin

    2012-07-16

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

  4. Assessment of highway pavements using GPR

    NASA Astrophysics Data System (ADS)

    Plati, Christina; Loizos, Andreas

    2015-04-01

    Highway infrastructure is a prerequisite for a functioning economy and social life. Highways, often prone to congestion and disruption, are one of the aspects of a modern transport network that require maximum efficiency if an integrated transport network, and sustainable mobility, is to be achieved. Assessing the condition of highway structures, to plan subsequent maintenance, is essential to allow the long-term functioning of a road network. Optimizing the methods used for such assessment will lead to better information being obtained about the road and underlying ground conditions. The condition of highway structures will be affected by a number of factors, including the properties of the highway pavement, the supporting sub-base and the subgrade (natural ground), and the ability to obtain good information about the entire road structure, from pavement to subgrade, allows appropriate maintenance programs to be planned. The maintenance of highway pavements causes considerable cost and in many cases obstruction to traffic flow. In this situation, methods that provide information on the present condition of pavement structure non-destructively and economically are of great interest. It has been shown that Ground-Penetrating-Radar (GPR), which is a Non Destructive Technique (NDT), can deliver information that is useful for the planning of pavement maintenance activities. More specifically GPR is used by pavement engineers in order to determine physical properties and characteristics of the pavement structure, information that is valuable for the assessment of pavement condition. This work gives an overview on the practical application of GPR using examples from highway asphalt pavements monitoring. The presented individual applications of GPR pavement diagnostics concern structure homogeneity, thickness of pavement layers, dielectric properties of asphalt materials etc. It is worthwhile mentioning that a number of applications are standard procedures, either separately or in combination with other NDT methods, but even for them there is still a room for improvement and there is still need to set stricter regulations Comparisons between radar results and ground truth data produce evidence in support of the statement that the accuracy and reliability of radar results is sufficient for facing many issues related to the evaluation of asphalt pavements. Thus, benefits and limits of this method are shown and recommendations for GPR inspections are presented. Acknowledgments: This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

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

    E-print Network

    Stanford University

    SAFEgress: A Flexible Platform to Study the Effect of Human and Social Behaviors on Egress to incorporate human and social behaviors during evacautions. Simulation results on two scenarios are presented safety. Despite observations and studies about human behaviors during emergencies, most simulation tools

  6. Coupled thermal electric-modeling of flexible nanospring interconnects for high-performance probing

    Microsoft Academic Search

    Mudasir Ahmad; Suresh K. Sitaraman

    2001-01-01

    Advances in integrated circuit fabrication have given rise to a need for an innovative, inexpensive, yet reliable probing technology with ultra-fine pitch capability. Research teams at Georgia Tech, Xerox PARC, and Nanonexus, Inc. Are developing flexible nanospring structures that can far exceed the probing needs of the next-generation microelectronic devices. Highly compliant cantilevered springs have been fabricated at pitches as

  7. Room temperature synthesis of cobalt-manganese-nickel oxalates micropolyhedrons for high-performance flexible electrochemical energy storage device.

    PubMed

    Zhang, Yi-Zhou; Zhao, Junhong; Xia, Jing; Wang, Lulu; Lai, Wen-Yong; Pang, Huan; Huang, Wei

    2015-01-01

    Cobalt-manganese-nickel oxalates micropolyhedrons were successfully fabricated by a room temperature chemical co-precipitation method. Interestingly, the Co0.5Mn0.4Ni0.1C2O4*nH2O micropolyhedrons and graphene nanosheets have been successfully applied as the positive and negative electrode materials (a battery type Faradaic electrode and a capacitive electrode, respectively) for flexible solid-state asymmetric supercapacitors. More importantly, the as-assembled device achieved a maximum energy density of 0.46?mWh·cm(-3), a decent result among devices with similar structures. The as-assembled device showed good flexibility, functioning well under both normal and bent conditions (0°-180°). The resulting device showed little performance decay even after 6000 cycles, which rendered the Co0.5Mn0.4Ni0.1C2O4*nH2O//Graphene device configuration a promising candidate for high-performance flexible solid-state asymmetric supercapacitors in the field of high-energy-density energy storage devices. PMID:25705048

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

    E-print Network

    Han, Rongbin

    2012-07-16

    in pavements. In this model, oxygen transport and reaction were described mathematically as two interlinked steps: 1) diffusion and/or flow of oxygen from the atmosphere above the pavement into the interconnected air voids in the pavement; and 2) diffusion...

  9. Pervious Pavement System Evaluation- Abstract 1

    EPA Science Inventory

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

  10. Concrete Pavement Sustainability Sustainability Track Leadership

    E-print Network

    #12;What Else is Happening? · FHWA advocating "Green Paving" technologies ­ Recycled concrete, twoTrack 13: Concrete Pavement Sustainability #12;Sustainability Track Leadership Committee Members: Preservation/Rehabilitation/Recycling Strategies · S.5: Improved Economic Life Cycle Cost Analysis · S.6

  11. Flexible transparent conducting composite films using a monolithically embedded AgNW electrode with robust performance stability

    NASA Astrophysics Data System (ADS)

    Im, Hyeon-Gyun; Jin, Jungho; Ko, Ji-Hoon; Lee, Jaemin; Lee, Jung-Yong; Bae, Byeong-Soo

    2013-12-01

    We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices.We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices. Electronic supplementary information (ESI) available: Further characteristics of AgNW-GFRHybrimer films and thermal oxidation of AgNW on glass. See DOI: 10.1039/c3nr05348b

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

    PubMed

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

    2013-09-24

    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

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

    Microsoft Academic Search

    Dariusz Sybilski; Wojciech Ba?kowski

    2002-01-01

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

  14. Reducing traffic noise with quieter pavements

    NASA Astrophysics Data System (ADS)

    Donavan, Paul

    2005-09-01

    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.

  15. Fusing complementary images for pavement cracking measurements

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  16. Solution processable colloidal nanoplates as building blocks for high-performance electronic thin films on flexible substrates.

    PubMed

    Lin, Zhaoyang; Chen, Yu; Yin, Anxiang; He, Qiyuan; Huang, Xiaoqing; Xu, Yuxi; Liu, Yuan; Zhong, Xing; Huang, Yu; Duan, Xiangfeng

    2014-11-12

    Low-temperature solution-processed electronic materials on plastic substrates are of considerable interest for flexible electronics. Solution dispersible inorganic nanostructures (e.g., zero-dimensional (0D) quantum dots or one-dimensional (1D) nanowires) have emerged as interesting ink materials for low-temperature solution processing of electronic thin films on flexible substrates, but usually with limited performance due to the large number of grain boundaries (0D) or incomplete surface coverage (1D). Here, we report two-dimensional (2D) colloidal nanoplates of layered materials as a new ink material for solution assembly of high-performance electronic thin films. The 2D colloidal nanoplates exhibit few dangling bonds and represent an ideal geometry for the assembly of highly uniform continuous thin films with greatly reduced grain boundaries dictated by large-area conformal plane-plane contact with atomically flat/clean interfaces. It can therefore promise efficient charge transport across neighboring nanoplates and throughout the entire thin film to enable unprecedented electronic performance. We show that Bi2Se3 and Bi2Te3 nanoplates can be synthesized with well-controlled thickness (6-15 nm) and lateral dimension (0.5-3 ?m) and can be used for the assembly of highly uniform continuous thin films with a full surface coverage and an excellent room temperature carrier mobility >100 cm(2)·V(-1)·s(-1), approaching that of chemical vapor deposition grown materials. Our study demonstrates a general strategy to using 2D nanoplates as a unique building block for the construction of high-performance electronic thin films on plastic substrates for future flexible electronics and optoelectronics. PMID:25343683

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

    PubMed

    Junwei, Zhang; Jinping, Li; Xiaojuan, Quan

    2013-01-01

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

  18. QUANTIFYING THE IMPACT OF JOINTED CONCRETE PAVEMENT CURLING AND WARPING ON PAVEMENT UNEVENNESS

    Microsoft Academic Search

    George K. Chang; Steven M. Karamihas; Robert Otto Rasmussen; David Merritt; Mark Swanlund

    Curling and warping of jointed concrete pavement (JCP) are well-known phenomena. It is a common belief that this behavior may impact pavement unevenness, and thus driver comfort. This relationship has been difficult to quantify in the past due to lack of adequate field measurements and appropriate analysis techniques. To address this issue, the United States Department of Transportation Federal Highway

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

    Microsoft Academic Search

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

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

  20. A sensitivity analysis of the Texas flexible pavement system 

    E-print Network

    Henry, Claude Patrick

    1991-01-01

    . stab. )Granular Base Thick. 12/10 6/6 ESAL 20E6 4E6 Pl Subgrade 10 Subgrade Modulus 7000 psi 18000 psi Surface Thickness 3. 5" 2. 0' Shoulder Type Paved Unpaved AC Type (Base} AC 20 AC 10 % Voids/% AC (Base) 5/7 7/4 Granular Base Mod Wus 60, 000... an increment of 1. 5 inches or a thickness of 3. 5 inches for the high value. As with the base thickness, a range of thicknesses can be used with the program for the surface layer and the program will determine the optimum thickness. ~Sho h~rT gl...

  1. A sensitivity analysis of the Texas flexible pavement system

    E-print Network

    Henry, Claude Patrick

    1991-01-01

    . GRANULAR BASE 1 YR, GRANULAR BASE 10 YR. ASPH STAB BASE 1 Y R, ASPH STAB BASE 10 Y R ASPH/GRN BASE 1 YR. ASPW/GRN BASE 10 YR. PSI 5 6 3 2 1 0 1 2 3 0 5 BEAUMONT DALHART Figure 3: PSI Comparison for Location and Time. GRANULAR BASE 1 YR. GRANULAR..., GRANULAR BASE 10 YR, ASPH STAB BASE 1 YR. ASP H STAB BASE 10 Y R ASPH/GRN BASE 1 YR, ASPH/GRN BASE 10 YR. RUT DEPTH Dn, ) 1 0 8 0, 6 0, 9 0 2 0 0 2 0, 'I 0. 6 0 8 I BEAUMONT DAL HART Figure 5i Rut Oepth Comparison Between Location and Time...

  2. Intra-seasonal flexibility in avian metabolic performance highlights the uncoupling of basal metabolic rate and thermogenic capacity.

    PubMed

    Petit, Magali; Lewden, Agnès; Vézina, François

    2013-01-01

    Stochastic winter weather events are predicted to increase in occurrence and amplitude at northern latitudes and organisms are expected to cope through phenotypic flexibility. Small avian species wintering in these environments show acclimatization where basal metabolic rate (BMR) and maximal thermogenic capacity (MSUM) are typically elevated. However, little is known on intra-seasonal variation in metabolic performance and on how population trends truly reflect individual flexibility. Here we report intra-seasonal variation in metabolic parameters measured at the population and individual levels in black-capped chickadees (Poecileatricapillus). Results confirmed that population patterns indeed reflect flexibility at the individual level. They showed the expected increase in BMR (6%) and MSUM (34%) in winter relative to summer but also, and most importantly, that these parameters changed differently through time. BMR began its seasonal increase in November, while MSUM had already achieved more than 20% of its inter-seasonal increase by October, and declined to its starting level by March, while MSUM remained high. Although both parameters co-vary on a yearly scale, this mismatch in the timing of variation in winter BMR and MSUM likely reflects different constraints acting on different physiological components and therefore suggests a lack of functional link between these parameters. PMID:23840843

  3. High-Performance Flexible Ultraviolet (UV) Phototransistor Using Hybrid Channel of Vertical ZnO Nanorods and Graphene.

    PubMed

    Dang, Vinh Quang; Trung, Tran Quang; Duy, Le Thai; Kim, Bo-Yeong; Siddiqui, Saqib; Lee, Wonil; Lee, Nae-Eung

    2015-05-27

    A flexible ultraviolet (UV) photodetector based on ZnO nanorods (NRs) as nanostructure sensing materials integrated into a graphene (Gr) field-effect transistor (FET) platform is investigated with high performance. Based on the negative shift of the Dirac point (VDirac) in the transfer characteristics of a phototransistor, high-photovoltage responsivity (RV) is calculated with a maximum value of 3 × 10(8) V W(-1). The peak response at a wavelength of ?365 nm indicated excellent selectivity to UV light. The phototransistor also allowed investigation of the photocurrent responsivity (RI) and photoconductive gain (G) at various gate voltages, with maximum values of 2.5 × 10(6) A W(-1) and 8.3 × 10(6), respectively, at a gate bias of 5 V. The UV response under bending conditions was virtually unaffected and was unchanged after 10?000 bending cycles at a bending radius of 12 mm, subject to a strain of 0.5%. The attributes of high stability, selectivity, and sensitivity of this flexible UV photodetector based on a ZnO NRs/Gr hybrid FET indicate promising potential for future flexible optoelectronic devices. PMID:25942324

  4. Intra-Seasonal Flexibility in Avian Metabolic Performance Highlights the Uncoupling of Basal Metabolic Rate and Thermogenic Capacity

    PubMed Central

    Petit, Magali; Lewden, Agnès; Vézina, François

    2013-01-01

    Stochastic winter weather events are predicted to increase in occurrence and amplitude at northern latitudes and organisms are expected to cope through phenotypic flexibility. Small avian species wintering in these environments show acclimatization where basal metabolic rate (BMR) and maximal thermogenic capacity (MSUM) are typically elevated. However, little is known on intra-seasonal variation in metabolic performance and on how population trends truly reflect individual flexibility. Here we report intra-seasonal variation in metabolic parameters measured at the population and individual levels in black-capped chickadees (Poecileatricapillus). Results confirmed that population patterns indeed reflect flexibility at the individual level. They showed the expected increase in BMR (6%) and MSUM (34%) in winter relative to summer but also, and most importantly, that these parameters changed differently through time. BMR began its seasonal increase in November, while MSUM had already achieved more than 20% of its inter-seasonal increase by October, and declined to its starting level by March, while MSUM remained high. Although both parameters co-vary on a yearly scale, this mismatch in the timing of variation in winter BMR and MSUM likely reflects different constraints acting on different physiological components and therefore suggests a lack of functional link between these parameters. PMID:23840843

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

    PubMed Central

    2013-01-01

    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

  6. RESEARCH Open Access Pavement crack characteristic detection based

    E-print Network

    Joensuu, University of

    are not caused by pavement distress such as tire marks, oil spills and shadows. In the field of 3D pavement crack distress such as tire marks, oil spills, shadows, and recent fillings [11]. Moreover, the shadows and poor

  7. POROUS PAVEMENT. PHASE I. DESIGN AND OPERATIONAL CRITERIA

    EPA Science Inventory

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

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

    PubMed

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

    2014-05-21

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

  9. Thermal performance of FRSI/graphite epoxy materials for the Orbiter TPS application. [Flexible Reusable Surface Insulation

    NASA Technical Reports Server (NTRS)

    Norman, I.; Ritrivi, C. A.; Tillian, D. J.; Maraia, R. J.

    1984-01-01

    Radiant tests have been conducted to evaluate the performance of the Flexible Reusable Surface Insulation (FRSI) when bonded to Graphite/Epoxy (G/E) honeycomb sandwich structures. The results from this study indicate reasonable agreement with the baseline FRSI properties that existed prior to this test program. An updated Thermal Math Model (TMM) prediction technique was developed, with the use of the well-defined boundary conditions, which appears to be valid in analyzing the complex heat transfer associated with the honeycomb structure. The updated TM analysis of flight data resulted in good agreement of predicted temperatures with flight data for bondline responses of Orbiter FRSI/GE TPS applications.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  11. Ultrahigh performance C60 nanorod large area flexible photoconductor devices via ultralow organic and inorganic photodoping.

    PubMed

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

    2014-01-01

    One dimensional single-crystal nanorods of C60 possess unique optoelectronic properties including high electron mobility, high photosensitivity and an excellent electron accepting nature. In addition, their rapid large scale synthesis at room temperature makes these organic semiconducting nanorods highly attractive for advanced optoelectronic device applications. Here, we report low-cost large-area flexible photoconductor devices fabricated using C60 nanorods. We demonstrate that the photosensitivity of the C60 nanorods can be enhanced ~400-fold via an ultralow photodoping mechanism. The photodoped devices offer broadband UV-vis-NIR spectral tuneability, exhibit a detectivitiy>10(9) Jones, an external quantum efficiency of ~100%, a linear dynamic range of 80?dB, a rise time 60?µs and the ability to measure ac signals up to ~250?kHz. These figures of merit combined are among the highest reported for one dimensional organic and inorganic large-area planar photoconductors and are competitive with commercially available inorganic photoconductors and photoconductive cells. With the additional processing benefits providing compatibility with large-area flexible platforms, these devices represent significant advances and make C60 nanorods a promising candidate for advanced photodetector technologies. PMID:24853479

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

    PubMed Central

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

    2014-01-01

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

  13. Molecular mechanisms controlling pavement cell shape in Arabidopsis leaves

    Microsoft Academic Search

    Pingping Qian; Suiwen Hou; Guangqin Guo

    2009-01-01

    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

  14. Surface Distresses Detection of Pavement Based on Digital Image Processing

    Microsoft Academic Search

    Aiguo Ouyang; Chagen Luo; Chao Zhou

    2010-01-01

    \\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

  15. Thermoelectric Generators using Solar Thermal Energy in Heated Road Pavement

    Microsoft Academic Search

    M. Hasebe; Y. Kamikawa; S. Meiarashi

    2006-01-01

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

  16. Effects of DNA probe and target flexibility on the performance of a "signal-on" electrochemical DNA sensor.

    PubMed

    Wu, Yao; Lai, Rebecca Y

    2014-09-01

    We report the effect of the length and identity of a nontarget binding spacer in both the probe and target sequences on the overall performance of a folding-based electrochemical DNA sensor. Six near-identical DNA probes were used in this study; the main differences between these probes are the length (6, 10, or 14 bases) and identity (thymine (T) or adenine (A)) of the spacer connecting the two target binding domains. Despite the differences, the signaling mechanism of these sensors remains essentially the same. The methylene blue (MB)-modified probe assumes a linear unstructured conformation in the absence of the target; upon hybridization to the target, the probe adopts a "close" conformation, resulting in an increase in the MB current. Among the six sensors, the T14 and A14 sensors showed the largest signal increase upon target hybridization, highlighting the significance of probe flexibility on sensor performance. In addition to the target without a midsequence spacer, 12 other targets, each with a different oligo-T or oligo-A spacer, were used to elucidate the effect of target flexibility on the sensors' signaling capacity. For all six sensors, hybridization to targets with a 2- or 3-base spacer resulted in the largest signal increase. Higher signal enhancement was also observed with targets with an oligo-A spacer. For this sensor design, addition of a long nontarget binding spacer to the probe sequence is advantageous, as it provides flexibility for optimal target capture. The length of the spacer in the target sequence, however, should be adequately long to enable efficient hybridization yet does not introduce undesirable electrostatic and crowding effects. PMID:25110351

  17. Aerodynamic performance of two-dimensional, chordwise flexible flapping wings at fruit fly scale in hover flight.

    PubMed

    Sridhar, Madhu; Kang, Chang-Kwon

    2015-01-01

    Fruit flies have flexible wings that deform during flight. To explore the fluid-structure interaction of flexible flapping wings at fruit fly scale, we use a well-validated Navier-Stokes equation solver, fully-coupled with a structural dynamics solver. Effects of chordwise flexibility on a two dimensional hovering wing is studied. Resulting wing rotation is purely passive, due to the dynamic balance between aerodynamic loading, elastic restoring force, and inertial force of the wing. Hover flight is considered at a Reynolds number of Re = 100, equivalent to that of fruit flies. The thickness and density of the wing also corresponds to a fruit fly wing. The wing stiffness and motion amplitude are varied to assess their influences on the resulting aerodynamic performance and structural response. Highest lift coefficient of 3.3 was obtained at the lowest-amplitude, highest-frequency motion (reduced frequency of 3.0) at the lowest stiffness (frequency ratio of 0.7) wing within the range of the current study, although the corresponding power required was also the highest. Optimal efficiency was achieved for a lower reduced frequency of 0.3 and frequency ratio 0.35. Compared to the water tunnel scale with water as the surrounding fluid instead of air, the resulting vortex dynamics and aerodynamic performance remained similar for the optimal efficiency motion, while the structural response varied significantly. Despite these differences, the time-averaged lift scaled with the dimensionless shape deformation parameter ?. Moreover, the wing kinematics that resulted in the optimal efficiency motion was closely aligned to the fruit fly measurements, suggesting that fruit fly flight aims to conserve energy, rather than to generate large forces. PMID:25946079

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

    ERIC Educational Resources Information Center

    Cason, Gerald J.; And Others

    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…

  19. Relationship Between Highway Pavement Condition, Crash Frequency, and Crash Type

    Microsoft Academic Search

    Chun Yip Chan; Baoshan Huang; Xuedong Yan; Stephen Richards

    2009-01-01

    Research has been conducted to relate highway pavement conditions with vehicle accidents. Utilizing the Tennessee Pavement Management System (PMS) and Accident History Database (AHD), this study developed 20 negative binomial regression models to examine the relationships between pavement condition parameters, crash frequency, and crash types. The modeling results indicated that either Present Serviceability Index (PSI) or International Roughness Index (IRI)

  20. STRUCTURAL AND DESIGN ASPECTS OF POROUS AND PERMEABLE BLOCK PAVEMENT

    Microsoft Academic Search

    S. Beecham; B. Myers

    Pavements are an intrinsic, seldom-thought-about part of life, particularly in urban areas. However, for developers, industrial facilities, and local authorities addressing stormwater and associated water quality guidelines and regulations, pavements stay very much at the forefront of planning issues. This is because impervious surfaces such as pavements have a major impact on water quality and on the health of natural

  1. EVOLUTIONAL PROCESS OF PAVEMENT ROUGHNESS EVALUATION BENEFITING FROM SENSOR TECHNOLOGY

    Microsoft Academic Search

    Andreas Loizos; Christina Plati

    2008-01-01

    The present paper deals with a view of the availability of high-speed sensor profilers, which has given dramatically increased possibilities to analyze imperfections in pavement surfaces such as roughness. Technical parameters of such profilers, for sensing and analyzing pavement surface profile are described. In addition, the main investigation concentrates on the evolutional process of pavement roughness evaluation. For this purpose

  2. Development on preventive maintenance management system for expressway asphalt pavements

    Microsoft Academic Search

    Hu Guoxiang; Li Jie

    2010-01-01

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

  3. Laser Scribing of High-Performance and Flexible Graphene-Based Electrochemical Capacitors

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

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

    PubMed Central

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

    2014-01-01

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

  5. Sliding mode attitude control with L 2-gain performance and vibration reduction of flexible spacecraft with actuator dynamics

    NASA Astrophysics Data System (ADS)

    Hu, Qinglei

    2010-09-01

    This paper presents a dual-stage control system design method for the rotational maneuver control and vibration stabilization of a flexible spacecraft. In this design approach, the sub-systems of attitude control and vibration suppression are designed separately using the low order model. Based on the sliding mode control (SMC) theory, a discontinuous attitude control law in the form of the input voltage of the reaction wheel is derived to control the orientation of the spacecraft, incorporating the L 2-gain performance criterion constraint. The resulting closed-loop system is proven to be uniformly ultimately bounded stability and the effect of the external disturbance on both attitude quaternion and angular velocity can be attenuated to the prescribed level as well. In addition, an adaptive version of the control law is designed for adapting the unknown upper bounds of the lumped disturbance such that the limitation of knowing the bound of the disturbance in advance is released. For actively suppressing the induced vibration, strain rate feedback control method is also investigated by using piezoelectric materials as additional sensors and actuators bonded on the surface of the flexible appendages. Numerical simulations are performed to show that rotational maneuver and vibration suppression are accomplished in spite of the presence of disturbance and uncertainty.

  6. Flexible one-dimensional carbon-selenium composite nanofibers with superior electrochemical performance for Li-Se/Na-Se batteries

    NASA Astrophysics Data System (ADS)

    Zeng, Linchao; Wei, Xiang; Wang, Jiaqing; Jiang, Yu; Li, Weihan; Yu, Yan

    2015-05-01

    A facile strategy is developed to synthesis selenium/carbon composites (Se@CNFs-CNT) by co-heating Se powder and electrospun Polyacrylonitrile (PAN)-CNT nanofibers at 600°Cin a sealed vessel. The Se molecules are chemically bonded and physical encapsulated by carbonized PAN-CNT composite (CNFs-CNT), which leads to prevent the dissolution of polyselenide intermediates in carbonate based electrolyte. When directly used as flexible free-standing cathode material for Li-Se batteries in low cost carbonate-based electrolyte, the Se@CNFs-CNT electrode exhibits improved cyclability (517 mAh g-1 after 500 cycles at 0.5 A g-1) and rate capability (485 mAh g-1 at 1 A g-1). Moreover, when tested as sodium batteries, it maintains a reversible capacity of 410 mAh g-1 after 240 cycles at 0.5 A g-1. The superior electrochemical performance (especially at high rates) of Se@CNFs-CNT is attributed to synergistic effect of the additive of CNT, the well confine of Se in the CNFs-CNT matrix through chemical bonding and the 3D interconnected carbon nanofibers (CNFs). This simple yet efficient process thus provides a promising route towards fabrication of a variety of high performance flexible Li-Se and Na-Se batteries.

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

    Microsoft Academic Search

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

    2011-01-01

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

  8. Automation of Pavement Surface Crack Detection using the Continuous Wavelet Transform

    Microsoft Academic Search

    Peggy Subirats; Jean Dumoulin; Vincent Legeay; Dominique Barba

    2006-01-01

    This paper presents a new approach in automation for crack detection on pavement surface images. The method is based on the continuous wavelet transform. In the first step, a separable 2D continuous wavelet transform for several scales is performed. Complex coefficient maps are built. The angle and modulus information are used to keep significant coefficients. Then, wavelet coefficients maximal values

  9. Monitoring Strategies in Permeable Pavement Systems to Optimize Maintenance Scheduling - abstract

    EPA Science Inventory

    As the surface in a permeable pavement system clogs and performance decreases, maintenance is required to preserve the design function. Currently, guidance is limited for scheduling maintenance on an as needed basis. Previous research has shown that surface clogging in a permea...

  10. Temperature control of hot-poured sealants during the sealing of pavement cracks

    Microsoft Academic Search

    J. F. Masson; P. Collins; M. Lowery

    2005-01-01

    Bituminous sealants are applied to asphalt concrete roadways to prevent the ingress of water, brine and debris in the road structure. This delays degradation and extends the pavement service life. Sealants are applied hot, yet little is known about temperature control and temperature variations during typical sealant installations and its affect on sealant properties and performance. To address this issue,

  11. TOLLWAY LCCA PROCESS FOR ADDAMS MEMORIAL TOLLWAY ADDAMS EXPRESSWAY PAVEMENT RECONSTRUCTION --

    E-print Network

    -- LIFE-CYCLE COST ANALYSIS BACKGROUND In 2012, the Illinois Tollway made the decision to reconstruct. The Tollway then performed a life-cycle cost analysis (LCCA) to determine the relative costs of five different, including: 2-lift, black rock Jointed Plain Concrete Pavement (JPCP) 2-lift, black rock Continuously

  12. Permeable Pavement Research at NRMRL?s Urban Watershed Research Facility

    EPA Science Inventory

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

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

    Microsoft Academic Search

    T. R. Burnham

    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

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

    NASA Astrophysics Data System (ADS)

    Reyff, James A.; Donavan, Paul

    2005-09-01

    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.

  15. Pavement Sealcoat, PAHs, and the Environment

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  16. Road Materials and Pavement Design, 2013 Vol. 14, No. S2, 5778, http://dx.doi.org/10.1080/14680629.2013.812838

    E-print Network

    Paulino, Glaucio H.

    to its flexible mastic matrix and particulate composite morphology. Significant energy is required to initiate and propagate a crack through asphalt concrete, as the asphalt mastic is tough, strain tolerant study by Islam and Buttlar (2012), pavements allowed to reach a rough conditio

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

    PubMed Central

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

    2014-01-01

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

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

    E-print Network

    Hoyt, Denise

    2012-07-16

    for evaluating macrotexture of pavements. The paper was published in the 2011 Transportation Research Record (8). The authors of the paper are Arash Rezaei, Denise Hoyt, and Amy Epps Martin. While the use of pavement cores to evaluate pavement macrotexture... (with nitrogen purge) The hot oven method is similar to the recovery method described in ASTM D244-97C (19) with the modification that nitrogen flows over the sample to prevent oxidation and consequent aging of the material. A beaker containing 50 g...

  19. Spills on Flat Inclined Pavements

    SciTech Connect

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

    2004-03-01

    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.

  20. Finite Element Investigation of the Deterioration of Doweled Rigid Pavements

    E-print Network

    Ziad G. Ghauch

    2013-06-23

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

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

    Microsoft Academic Search

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

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

  2. Self-poled transparent and flexible UV light-emitting cerium complex-PVDF composite: a high-performance nanogenerator.

    PubMed

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

    2015-01-21

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

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

    Microsoft Academic Search

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

    2001-01-01

    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

  4. Chemically doped three-dimensional porous graphene monoliths for high-performance flexible field emitters

    NASA Astrophysics Data System (ADS)

    Kim, Ho Young; Jeong, Sooyeon; Jeong, Seung Yol; Baeg, Kang-Jun; Han, Joong Tark; Jeong, Mun Seok; Lee, Geon-Woong; Jeong, Hee Jin

    2015-03-01

    Despite the recent progress in the fabrication of field emitters based on graphene nanosheets, their morphological and electrical properties, which affect their degree of field enhancement as well as the electron tunnelling barrier height, should be controlled to allow for better field-emission properties. Here we report a method that allows the synthesis of graphene-based emitters with a high field-enhancement factor and a low work function. The method involves forming monolithic three-dimensional (3D) graphene structures by freeze-drying of a highly concentrated graphene paste and subsequent work-function engineering by chemical doping. Graphene structures with vertically aligned edges were successfully fabricated by the freeze-drying process. Furthermore, their number density could be controlled by varying the composition of the graphene paste. Al- and Au-doped 3D graphene emitters were fabricated by introducing the corresponding dopant solutions into the graphene sheets. The resulting field-emission characteristics of the resulting emitters are discussed. The synthesized 3D graphene emitters were highly flexible, maintaining their field-emission properties even when bent at large angles. This is attributed to the high crystallinity and emitter density and good chemical stability of the 3D graphene emitters, as well as to the strong interactions between the 3D graphene emitters and the substrate.Despite the recent progress in the fabrication of field emitters based on graphene nanosheets, their morphological and electrical properties, which affect their degree of field enhancement as well as the electron tunnelling barrier height, should be controlled to allow for better field-emission properties. Here we report a method that allows the synthesis of graphene-based emitters with a high field-enhancement factor and a low work function. The method involves forming monolithic three-dimensional (3D) graphene structures by freeze-drying of a highly concentrated graphene paste and subsequent work-function engineering by chemical doping. Graphene structures with vertically aligned edges were successfully fabricated by the freeze-drying process. Furthermore, their number density could be controlled by varying the composition of the graphene paste. Al- and Au-doped 3D graphene emitters were fabricated by introducing the corresponding dopant solutions into the graphene sheets. The resulting field-emission characteristics of the resulting emitters are discussed. The synthesized 3D graphene emitters were highly flexible, maintaining their field-emission properties even when bent at large angles. This is attributed to the high crystallinity and emitter density and good chemical stability of the 3D graphene emitters, as well as to the strong interactions between the 3D graphene emitters and the substrate. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07189a

  5. An evaluation of pavement markings and raised pavement markers at left exit lane drops

    E-print Network

    Lance, Marty Tina

    1994-01-01

    components; more drivers are affected, interactions in the traffic stream are more turbulent, and the potential for confusion and accidents is substantially greater. Exit-only signs and pavement markings are two methods used to communicate an exit lane drop...

  6. High-resolution Sensing Sheet for Structural-health Monitoring via Scalable Interfacing of Flexible Electronics with High-performance ICs

    E-print Network

    are patterned on both the LAE sheet and on the flex-tape packaging of the ICs. We achieve assembly via sheet Electronics with High-performance ICs Yingzhe Hu, Warren Rieutort-Louis, Josue Sanz-Robinson, Katherine Song that combines high-performance ICs with flexible electronics, allowing bonding to such surfaces. The flexi ble

  7. A low power unified cache architecture providing power and performance flexibility (poster session)

    Microsoft Academic Search

    Afzal Malik; Bill Moyer; Dan Cermak

    2000-01-01

    Advances in technology have allowed portable electronic devices to become smaller and more complex, placing stringent power and performance requirements on the devices components. The M7CORE M3 architecture was developed specifically for these embedded applications. To address the growing need for longer battery life and higher performance, an 8-Kbyte, 4-way set-associative, unified (instruction and data) cache with pro-grammable features was

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

    PubMed Central

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

    2013-01-01

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

  9. An Efficient Finite Element Framework to Assess Flexibility Performances of SMA Self-Expandable Carotid Artery Stents.

    PubMed

    Ferraro, Mauro; Auricchio, Ferdinando; Boatti, Elisa; Scalet, Giulia; Conti, Michele; Morganti, Simone; Reali, Alessandro

    2015-01-01

    Computer-based simulations are nowadays widely exploited for the prediction of the mechanical behavior of different biomedical devices. In this aspect, structural finite element analyses (FEA) are currently the preferred computational tool to evaluate the stent response under bending. This work aims at developing a computational framework based on linear and higher order FEA to evaluate the flexibility of self-expandable carotid artery stents. In particular, numerical simulations involving large deformations and inelastic shape memory alloy constitutive modeling are performed, and the results suggest that the employment of higher order FEA allows accurately representing the computational domain and getting a better approximation of the solution with a widely-reduced number of degrees of freedom with respect to linear FEA. Moreover, when buckling phenomena occur, higher order FEA presents a superior capability of reproducing the nonlinear local effects related to buckling phenomena. PMID:26184329

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

    ERIC Educational Resources Information Center

    Giardina, Michael D.

    2009-01-01

    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,…

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

    Microsoft Academic Search

    D. Kearns

    2003-01-01

    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

  12. Deep Thinking Increases Task-Set Shielding and Reduces Shifting Flexibility in Dual-Task Performance

    ERIC Educational Resources Information Center

    Fischer, Rico; Hommel, Bernhard

    2012-01-01

    Performing two tasks concurrently is difficult, which has been taken to imply the existence of a structural processing bottleneck. Here we sought to assess whether and to what degree one's multitasking abilities depend on the cognitive-control style one engages in. Participants were primed with creativity tasks that either called for divergent…

  13. PAVEMENT TECHNOLOGY UPDATE This Technology Transfer Program

    E-print Network

    California at Berkeley, University of

    reduces worker exposure to asphalt fumes at the plant and during the construction of the asphalt pavement, and industry. Introduction Warm Mix Asphalt (WMA) has the potential for being one of the most important break- throughs for the asphalt industry in 50 years [1]. WMA was introduced in Europe in 1995 and debuted

  14. Desert pavement study at Amboy, California

    NASA Technical Reports Server (NTRS)

    Williams, S.; Greeley, R.

    1984-01-01

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

  15. End-to-end performance evaluation methodology for TWTA-based satellite flexible payloads

    Microsoft Academic Search

    Marinella Aloisio; Piero Angeletti; Enrico Colzi; Salvatore D'Addio; Roger Oliva Balague; Enrico Casini; Francesc Coromina

    2008-01-01

    Reconfigurability of the RF power among different beams and channels is of primary interest in communications satellite systems for its potentiality in maximizing the payload bandwidth and power utilization over the satellite lifetime. The performance of reconfigurable payloads strictly depends on the architecture of the high-power section. We will compare two multi-amplifier architectures, one based on bias-adjustable Traveling-wave Tubes, the

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

    PubMed

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

    2014-02-17

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

  17. Selection for Growth Performance in Broiler Chickens Associates with Less Diet Flexibility

    PubMed Central

    Pauwels, Jana; Coopman, Frank; Cools, An; Michiels, Joris; Fremaut, Dirk; De Smet, Stefaan; Janssens, Geert P. J.

    2015-01-01

    Global competition for high standard feed-food resources between man and livestock, such as industrial broilers, is a concerning problem. In addition, the low productivity of scavenger chickens in developing countries leaves much to be desired. Changing the ingredients, and therefore, the nutrient composition of feed intake by commercial fed as well as scavenger chickens seems like an obvious solution. In this study, the ability of four broiler chicken breeds to perform on a commercial versus a scavenger diet was tested. The four broiler breeds differed genetically in growth potential. A significant (P < 0.01) negative effect of the scavenger diet on the bodyweight of the fast growing breeds was found and this effect decreased with decreasing growth rate in the other breeds. These differences in bodyweight gain could not be explained by differences in nutrient digestibility but were caused by the lack of ability of the fast growing breeds to increase their feed intake sufficiently. PMID:26042600

  18. Selection for growth performance in broiler chickens associates with less diet flexibility.

    PubMed

    Pauwels, Jana; Coopman, Frank; Cools, An; Michiels, Joris; Fremaut, Dirk; De Smet, Stefaan; Janssens, Geert P J

    2015-01-01

    Global competition for high standard feed-food resources between man and livestock, such as industrial broilers, is a concerning problem. In addition, the low productivity of scavenger chickens in developing countries leaves much to be desired. Changing the ingredients, and therefore, the nutrient composition of feed intake by commercial fed as well as scavenger chickens seems like an obvious solution. In this study, the ability of four broiler chicken breeds to perform on a commercial versus a scavenger diet was tested. The four broiler breeds differed genetically in growth potential. A significant (P < 0.01) negative effect of the scavenger diet on the bodyweight of the fast growing breeds was found and this effect decreased with decreasing growth rate in the other breeds. These differences in bodyweight gain could not be explained by differences in nutrient digestibility but were caused by the lack of ability of the fast growing breeds to increase their feed intake sufficiently. PMID:26042600

  19. Flexible copper-stabilized sulfur-carbon nanofibers with excellent electrochemical performance for Li-S batteries.

    PubMed

    Zeng, Linchao; Jiang, Yu; Xu, Jun; Wang, Min; Li, Weihan; Yu, Yan

    2015-07-01

    By rational design, we fabricated a flexible and free-standing copper-immobilized sulfur-porous carbon nanofiber (denoted as S@PCNFs-Cu) electrode by simply impregnating sulfur into electrospun derived Cu embedded porous carbon nanofibers (PCNFs-Cu). The PCNF film with a 3D interconnected structure is used as a conducting matrix to encapsulate sulfur. In addition, the introduction of Cu leads to the formation of a chemical bond between Cu and S, preventing the dissolution of polysulfide during cycling. The micropores and mesopores of PCNF hosts provide free space to accommodate the volume change of S and polysulfide. When used as a cathode material for Li-S batteries, the S@PCNFs-Cu (S content: 52 wt%) exhibits much better electrochemical performance compared to the Cu-free S@PCNF electrode. The S@PCNFs-Cu displays high reversible capacity (680 mA h g(-1) after 100 cycles at 50 mA g(-1)), excellent rate capability (415 mA h g(-1) at 1 A g(-1)) and super Coulombic efficiency of 100%. This strategy of stabilizing S with a small amount of copper nanoparticles can be a very promising method to prepare free-standing cathode material for high-performance Li-S batteries. PMID:26059471

  20. Flexible copper-stabilized sulfur-carbon nanofibers with excellent electrochemical performance for Li-S batteries

    NASA Astrophysics Data System (ADS)

    Zeng, Linchao; Jiang, Yu; Xu, Jun; Wang, Min; Li, Weihan; Yu, Yan

    2015-06-01

    By rational design, we fabricated a flexible and free-standing copper-immobilized sulfur-porous carbon nanofiber (denoted as S@PCNFs-Cu) electrode by simply impregnating sulfur into electrospun derived Cu embedded porous carbon nanofibers (PCNFs-Cu). The PCNF film with a 3D interconnected structure is used as a conducting matrix to encapsulate sulfur. In addition, the introduction of Cu leads to the formation of a chemical bond between Cu and S, preventing the dissolution of polysulfide during cycling. The micropores and mesopores of PCNF hosts provide free space to accommodate the volume change of S and polysulfide. When used as a cathode material for Li-S batteries, the S@PCNFs-Cu (S content: 52 wt%) exhibits much better electrochemical performance compared to the Cu-free S@PCNF electrode. The S@PCNFs-Cu displays high reversible capacity (680 mA h g-1 after 100 cycles at 50 mA g-1), excellent rate capability (415 mA h g-1 at 1 A g-1) and super Coulombic efficiency of 100%. This strategy of stabilizing S with a small amount of copper nanoparticles can be a very promising method to prepare free-standing cathode material for high-performance Li-S batteries.

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

    SciTech Connect

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

    1995-05-01

    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.

  2. Rapid cognitive flexibility of rhesus macaques performing psychophysical task-switching

    PubMed Central

    Avdagic, Ema; Jensen, Greg; Altschul, Drew

    2014-01-01

    Three rhesus monkeys (Macaca mulatta) performed a simultaneous chaining task in which stimuli had to be sorted according to their visual properties. Each stimulus could vary independently along two dimensions (luminosity and radius), and a cue indicating which dimension to sort by was random trial to trial. These rapid and unpredictable changes constitute a task-switching paradigm, in which subjects must encode task demands and shift to whichever task-set is presently activated. In contrast to the widely reported task-switching delay observed in human studies, our subjects show no appreciable reduction in reaction times following a switch in the task requirements. Also, in contrast to the results of studies on human subjects, monkeys experienced enduring interference from trial-irrelevant stimulus features, even after exhaustive training. These results are consistent with a small but growing body of evidence that task-switching in rhesus macaques differs in basic ways from the pattern of behavior reported in studies of human cognition. Given the importance of task-switching paradigms in cognitive and clinical assessment, and the frequency with which corresponding animal models rely on non-human primates, understanding these differences in behavior is essential to the comparative study of cognitive impairment. PMID:24132412

  3. Development of Longitudinal Cracks on Pavement over Shrinking Expansive Subgrade

    Microsoft Academic Search

    Rong Luo; Jorge A. Prozzi

    2010-01-01

    The volumetric change of expansive clays in pavement subgrade produces serious pavement distresses. Dry-land longitudinal cracking is one of the most prevalent pavement distresses due to expansive subgrade. However, the mechanism of the dry-land crack development has not been addressed in depth, and the propagation process of dry-land cracks has not yet been clarified. This paper investigates the mechanism of

  4. Performance oriented packaging testing of the six-foot flexible linear shaped charge box for packing group II hazardous materials. Final report

    SciTech Connect

    Libbert, K.J.

    1992-10-01

    The wood box (Drawing 53711-6665109) for six-foot flexible linear shaped charges was tested for conformance to Performance Oriented Packaging standards specified by the Code of Federal Regulations, Title 49 CFR, Parts 107 through 178, dated 31 December 1991. The box was tested with a gross weight of 14 kilograms and met all the requirements.

  5. Hybrid green permeable pave with hexagonal modular pavement systems

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  6. Effect of Measured Three-Dimensional Tire-Pavement Contact Stress on Pavement Response at Asphalt Surface

    Microsoft Academic Search

    Rong Luo; Jorge A. Prozzi

    2007-01-01

    Top-down cracking results from horizontal strains at the pavement surface that are caused by high wheel loads. When horizontal strains are calculated, the tire–pavement contact stress is assumed to be equal to the tire inflation pressure and to be distributed uniformly over a circular area. In reality, tire–pavement contact stress is distributed nonuniformly over a noncircular area. Actual contact stresses

  7. MoO3 Nanodots Decorated CdS Nanoribbons for High-Performance, Homojunction Photovoltaic Devices on Flexible Substrates.

    PubMed

    Shao, Zhibin; Jie, Jiansheng; Sun, Zheng; Xia, Feifei; Wang, Yuming; Zhang, Xiaohong; Ding, Ke; Lee, Shuit-Tong

    2015-05-13

    The p-n homojunctions are essential components for high-efficiency optoelectronic devices. However, the lack of p-type doping in CdS nanostructures hampers the fabrication of efficient photovoltaic (PV) devices from homojunctions. Here we report a facile solution-processed method to achieve efficient p-type doping in CdS nanoribbons (NRs) via a surface charge transfer mechanism by using spin-coated MoO3 nanodots (NDs). The NDs-decorated CdS NRs exhibited a hole concentration as high as 8.5 × 10(19) cm(-3), with the p-type conductivity tunable in a wide range of 7 orders of magnitude. The surface charge transfer mechanism was characterized in detail by X-ray photoelectron spectroscopy, Kelvin probe force microscopy, and first-principle calculations. CdS NR-homojunction PV devices fabricated on a flexible substrate exhibited a power conversion efficiency of 5.48%, which was significantly better than most of the CdS nanostructure-based heterojunction devices, presumably due to minimal junction defects. Devices made by connecting cells in series or in parallel exhibited enhanced power output, demonstrating the promising potential of the homojunction PV devices for device integration. Given the high efficiency of the surface charge transfer doping and the solution-processing capability of the method, our work opens up unique opportunities for high-performance, low-cost optoelectronic devices based on CdS homojunctions. PMID:25866955

  8. Flexible Satellite Systems

    Microsoft Academic Search

    Philip J. Lin; Thomas J. Kostas

    2007-01-01

    In today's unpredictable and dynamic environment, flexibility is an important aspect in system design. Flexibility increases system capability and effectiveness, reduces long term cost, encourages innovation, and protects against uncertainty. It is often at odds with optimization. High cost and harsh environment lead to specialized high performance satellite systems with stringent size, weight, and power constraints. These inflexible systems are

  9. Smart Road Pavement Research HomePage

    NSDL National Science Digital Library

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

  10. Infiltration performance of engineered surfaces commonly used for distributed stormwater management

    NASA Astrophysics Data System (ADS)

    Valinski, Nicholas A.

    Engineered porous media are commonly used in low impact development (LID) structures to mitigate excess stormwater in urban environments. Differences in infiltrability of these LID systems arise from the wide variety of materials used to create porous surfaces and subsequent maintenance, debris loading, and physical damage. In this study, infiltration capacity of six common materials was tested by multiple replicate experiments with automated mini-disk infiltrometers. The tested materials included porous asphalt, porous concrete, porous brick pavers, flexible porous pavement, engineered soils, and native soils. Porous asphalt, large porous brick pavers, and curb cutout rain gardens showed the greatest infiltration rates. Most engineered porous pavements and soils performed better than the native silt loam soils. Infiltration performance was found to be related more to site design and environmental factors than material choice. Sediment trap zones in both pavements and engineered soil rain gardens were found to be beneficial to the whole site performance. Winter chloride application had a large negative impact on poured in place concrete, making it a poor choice for heavily salted areas.

  11. Characterizing a porous road pavement using surface impedance measurement: a guided numerical inversion procedure.

    PubMed

    Benoit, Gaëlle; Heinkélé, Christophe; Gourdon, Emmanuel

    2013-12-01

    This paper deals with a numerical procedure to identify the acoustical parameters of road pavement from surface impedance measurements. This procedure comprises three steps. First, a suitable equivalent fluid model for the acoustical properties porous media is chosen, the variation ranges for the model parameters are set, and a sensitivity analysis for this model is performed. Second, this model is used in the parameter inversion process, which is performed with simulated annealing in a selected frequency range. Third, the sensitivity analysis and inversion process are repeated to estimate each parameter in turn. This approach is tested on data obtained for porous bituminous concrete and using the Zwikker and Kosten equivalent fluid model. This work provides a good foundation for the development of non-destructive in situ methods for the acoustical characterization of road pavements. PMID:25669290

  12. Performance and stability of TiO 2\\/dye solar cells assembled with flexible electrodes and a polymer electrolyte

    Microsoft Academic Search

    Claudia Longo; Jilian Freitas; Marco-A. De Paoli

    2003-01-01

    Solid-state, flexible TiO2\\/dye solar cells were assembled using flexible electrodes, a polymer electrolyte with I?\\/I3? and a Pt coated counter-electrode. The efficiency of the cells was enhanced when the plastic electrodes coated with TiO2 were exposed to UV radiation, followed by heating at 140°C in dry conditions. For comparison, a similar cell was prepared by the same procedure but using

  13. Use of coal ash in highway pavements: Kansas Demonstration Project

    SciTech Connect

    Ferguson, G.; Zey, J.

    1992-01-01

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

  14. Airport pavement roughness evaluation based on aircraft response

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

    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.

  15. Environmental analysis of new construction and maintenance processes of road pavements in Switzerland

    Microsoft Academic Search

    Florian Gschösser; Holger Wallbaum; Bryan T. Adey

    2012-01-01

    The subject of this paper is an environmental analysis of processes needed to construct (material production, pavement construction, transport) and maintain (pavement deconstruction, recycling, material production, pavement construction, transport) representative Swiss asphalt, concrete and composite pavements (including subbase layers). The analysed environmental indicators are the IPCC Global Warming Potential indicator, the Ecological Scarcity Indicator and the Non-renewable Cumulative Energy Demand

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

    Microsoft Academic Search

    K. Kubo; H. KIDO

    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

  17. Utilization of Information Technology to Enhance an Asphalt Pavement Condition Evaluation Program

    Microsoft Academic Search

    Yichang Tsai; James L. Lai

    2001-01-01

    Accurate and consistent pavement condition evaluations are essential for developing reliable pavement maintenance management systems. The Georgia Department of Transportation (GDOT) has developed a Pavement Condition Evaluation System (PACES) to meet this need. PACES has been used to evaluate the pavement conditions on the entire highway system in Georgia annually since 1986, and the results have been used for developing

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

    PubMed

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

    2013-11-15

    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

  19. 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...

  20. Cosmogenic 3 He surface-exposure dating of stone pavements

    E-print Network

    Ahmad, Sajjad

    geologic time scales and to test this new model. These exposure ages are stratigraphically consistent, show at the land surface in a time-transgressive manner. A newly proposed model for pavement evolution differs from at the surface and that pavements may provide one of the longest-term records of geologic, hydrologic

  1. Weed occurrence on pavements in five North European towns

    Microsoft Academic Search

    B. Melander; N. Holst; A C GRUNDY; C. Kempenaar; M. M. Riemens; A. Verschwele; D. Hansson

    2009-01-01

    Weeds on pavements in urban areas are unwanted mainly because they cause an untidy appearance or sometimes structural damage. Glyphosate has been the principal weed control method for years, but policies in several European towns have changed to lower dependence on herbicides. Instead, less effective and more species-dependent non-chemical methods are used, but little is known about the pavement flora.

  2. THE EFFECT OF PAVEMENT SPLIT FRICTION PROVISION ON HIGHWAY CURVES

    Microsoft Academic Search

    Tang-Hsien Chang

    1997-01-01

    From the perspective of sprung vehicle dynamics, the design criteria of superelevation or radius is unsatisfactory for broad requirements. Superelevation design has many limitations. Therefore, in this study, we describe a split layout of pavement friction, designed to counterbalance an insufficiency of superelevation. The layout is to provide different friction pavements between the left and the right sides of a

  3. PRECAST CONCRETE PAVEMENT SLAB SYSTEMS (Tollway) Effective: March 30. 2009

    E-print Network

    braced, and shall be anchored, so as to withstand the forces due to vibratory placement of the concretePRECAST CONCRETE PAVEMENT SLAB SYSTEMS (Tollway) Effective: March 30. 2009 DESCRIPTION This specification covers material and fabrication requirements for precast concrete pavement slab systems

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

    E-print Network

    Provision; 2. Supplying and installing all specified reinforcement; 3. Developing concrete mix design(s cementitious material in any mix design. This special provision only applies to a concrete composite pavement Special Provision for Ternary Concrete Mix Designs for Composite Pavement. Concrete supplied for the top

  5. Pavement recycling-bituminous concrete and concrete mix designs

    Microsoft Academic Search

    R. Christman

    1979-01-01

    Trial mixes developed from both salvaged bituminous concrete and portland cement concrete pavement materials were tested in the laboratory. Salvaged materials investigated included crushed and cold milled bituminous concrete and crushed 40 x 12 ft concrete pavement slabs with wire mesh reinforcing. Laboratory results indicated the feasibility of full scale bituminous recyling projects using central plant mixing of salvaged and

  6. Field investigation of clogging in a permeable pavement system

    Microsoft Academic Search

    Terry Lucke; Simon Beecham

    2011-01-01

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

  7. Permeable Pavement Demonstration at the Edison Environmental Center (Hartford)

    EPA Science Inventory

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

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

    EPA Science Inventory

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

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

    E-print Network

    Paris-Sud XI, Université de

    of cooling dense urban areas and reducing the urban heat11 island effect has been studied since the 1990's; pavement heat flux; pavement-watering; urban heat island; climate change25 adaptation; heat wave26 1 [3], this technique is viewed as an efficient means of reducing urban31 heat island (UHI) intensity

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

    Microsoft Academic Search

    S. K. Saxena; S. G. Militsopoulos

    1980-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    PubMed

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

    2007-01-01

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

  13. A Review on Using Crumb Rubber in Reinforcement of Asphalt Pavement

    PubMed Central

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

    2014-01-01

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

  14. Flexible superior electrode architectures based on three-dimensional porous spinous ?-Fe2O3 with a high performance as a supercapacitor.

    PubMed

    Nan, Honghong; Yu, Liutao; Ma, Wenqin; Geng, Baoyou; Zhang, Xiaojun

    2015-05-12

    Flexible supercapacitors have recently attracted increasing attention as they show unique promising advantages, such as flexibility and shape diversity, and they are light-weight and so on. Herein, we designed a series of 3D porous spinous iron oxide materials synthesized on a thin iron plate through a facile method under mild conditions. The unique nanostructural features endow them with excellent electrochemical performance. The electrochemical properties of the integrated electrodes as active electrode materials for supercapacitors have been investigated using different electrochemical techniques including cyclic voltammetry, and galvanostatic charge-discharge in Na2SO4 and LiPF6/EC?:?DEC electrolyte solutions. These integrated electrodes showed high specific capacitance (as high as 524.6 F g(-1) at the current density of 1 A g(-1)) in 1.0 M Na2SO4 (see Table S1). Moreover, the integrated electrodes also show high power densities and high energy densities in a LiPF6/EC?:?DEC electrolyte solution; for example, the energy densities were 319.3, 252.5, 152.1, 74.13 and 38.6 W h kg(-1) at different power densities of 8.81, 21.59, 56.65, 92.09 and 152.64 kW kg(-1), respectively. Additionally, the flexible superior electrode exhibited excellent stability with capacitance retention of 92.9% after 5000 cycles. Therefore, such flexible integrated devices might be used in smart and portable electronics. PMID:25921621

  15. Proportioning of Steel Fibre Reinforced Concrete Mixes for Pavement Construction and Their Impact on Environment and Cost

    Microsoft Academic Search

    Constantia Achilleos; Diofantos Hadjimitsis; Kyriacos Neocleous; Kypros Pilakoutas; Pavlos O. Neophytou; Stelios Kallis

    2011-01-01

    Steel fibre reinforced concrete (SFRC) is a construction material investigated for more than 40 years including for pavement applications. A number of studies have demonstrated the technical merits of SFRC pavements over conventional concrete pavements; however little work has been carried out on the environmental and economical impact of SFRC during the pavement’s life cycle. Therefore, extended research was undertaken

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  17. The importance of the glass transition temperature in relation to the low-temperature fracture resistance of asphalt and sulphlex pavement binders

    E-print Network

    Smith, Douglas Lee

    1985-01-01

    in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1985 Major Subject: Civil Engineering THE IMPORTANCE OF THE GLASS TRANSITION TEMPERATURE IN RELATION TO THE LOW-TENPERATURE FRACTURE RESISTANCE OF ASPHALT AND SULPHLEX... possible binder material for use in both flexible and rigid pavement systems. Sulfur possesses excellent engineering properties both alone and when combined with other materials. Sulfur may be obtained from several different sources, including recovery...

  18. Sliding mode attitude control with L 2-gain performance and vibration reduction of flexible spacecraft with actuator dynamics

    Microsoft Academic Search

    Qinglei Hu

    2010-01-01

    This paper presents a dual-stage control system design method for the rotational maneuver control and vibration stabilization of a flexible spacecraft. In this design approach, the sub-systems of attitude control and vibration suppression are designed separately using the low order model. Based on the sliding mode control (SMC) theory, a discontinuous attitude control law in the form of the input

  19. Tire Footprint Affects Hydroplaning On Wet Pavement

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.

    1989-01-01

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

  20. Pavement cracking measurements using 3D laser-scan images

    NASA Astrophysics Data System (ADS)

    Ouyang, W.; Xu, B.

    2013-10-01

    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.

  1. Assessment of in-situ compaction degree of HMA pavement surface layers using GPR and novel dielectric properties-based algorithms

    NASA Astrophysics Data System (ADS)

    Georgiou, Panos; Loizos, Fokion

    2015-04-01

    Field compaction of asphalt pavements is ultimately conducted to achieve layer(s) with suitable mechanical stability. However, the achieved degree of compaction has a significant influence on the performance of asphalt pavements. Providing all desirable mixture design characteristics without adequate compaction could lead to premature permanent deformation, excessive aging, and moisture damage; these distresses reduce the useful life of asphalt pavements. Hence, proper construction of an asphalt pavement is necessary to develop a long lasting roadway that will help minimize future maintenance. This goal is achieved by verifying and confirming that design specifications, in this case density specifications are met through the use of Quality Assurance (QA) practices. With respect to in-situ compaction degree of hot mix asphalt (HMA) pavement surface layers, nearly all agencies specify either cored samples or nuclear/ non nuclear density gauges to provide density measurement of the constructed pavement. Typically, a small number of spot tests (with either cores or nuclear gauges) are run and a judgment about the density level of the entire roadway is made based on the results of this spot testing. Unfortunately, density measurement from a small number of spots may not be representative of the density of the pavement mat. Hence, full coverage evaluation of compaction quality of the pavement mat is needed. The Ground Penetrating Radar (GPR), as a Non Destructive Testing (NDT) technique, is an example of a non-intrusive technique that favors over the methods mentioned above for assessing compaction quality of asphalt pavements, since it allows measurement of all mat areas. Further, research studies in recent years have shown promising results with respect to its capability, coupled with the use of novel algorithms based on the dielectric properties of HMA, to predict the in-situ field density. In view of the above, field experimental surveys were conducted to assess the effectiveness of GPR methodology to estimate the in-situ compaction degree of several test sections. Moreover, considering also the field density results as obtained with traditional methods, comparative evaluation was conducted to assess the potential of using the GPR technique as a surrogate tool for pavement compaction quality purposes. Acknowledgements: This work has been inspired from publications of the COST action TU-1208 funded from EU.

  2. High-Performance Flexible Perovskite Solar Cells by Using a Combination of Ultrasonic Spray-Coating and Low Thermal Budget Photonic Curing

    SciTech Connect

    Sanjib, Das [University of Tennessee, Knoxville (UTK); Yang, Bin [ORNL; Gu, Gong [University of Tennessee, Knoxville (UTK); Joshi, Pooran C [ORNL; Ivanov, Ilia N [ORNL; Rouleau, Christopher [ORNL; Aytug, Tolga [ORNL; Geohegan, David B [ORNL; Xiao, Kai [ORNL

    2015-01-01

    Realizing the commercialization of high-performance and robust perovskite solar cells urgently requires the development of economically scalable processing techniques. Here we report a high-throughput ultrasonic spray-coating (USC) process capable of fabricating perovskite film-based solar cells on glass substrates with power conversion efficiency (PCE) as high as 13.04%. Perovskite films with high uniformity, crystallinity, and surface coverage are obtained in a single step. Moreover, we report USC processing on TiOx/ITO-coated polyethylene terephthalate (PET) substrates to realize flexible perovskite solar cells with PCE as high as 8.02% that are robust under mechanical stress. In this case, an optical curing technique was used to achieve a highly-conductive TiOx layer on flexible PET substrates for the first time. The high device performance and reliability obtained by this combination of USC processing with optical curing appears very promising for roll-to-roll manufacturing of high-efficiency, flexible perovskite solar cells.

  3. Use of lug anchors to related pavement movement

    NASA Astrophysics Data System (ADS)

    Oakey, S. A.

    1980-04-01

    Minnesota Department of Transporatation's policy is that grades in the 3 to 5 percent and greater range are steep and may require lug anchors. Standard lug anchor spacing varies from 150 feet, center to center, for 3 percent grades to 75 feet, center to center, for 5 percent and greater grades. Conclusions are: (1) that lug anchors do prevent the downhill movement of the concrete pavement; (2) that when lug anchors are used a perforated pipe system also be built to collect the surface water that enters the pavement structure thus eliminating the anticipated base pumping and pavement settlement.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    E-print Network

    Paris-Sud XI, Université de

    of glass fiber grids in pavement reinforcement. Then some results of recent full scale tests of the reinforced pavement. They also demonstrate the efficiency of glass grid use under only a thin asphalt overlay structure are described. KEYWORDS: Glass fiber grid, Reinforcement, Asphalt pavement, Reflective cracking

  7. Low-cost, flexible graphene/polyaniline nanocomposite paper as binder-free high-performance supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Wang, Li; Lv, Siliu; Zhang, Jianming; Zhang, Chuanjian; Dong, Shanmu; Kong, Qingshan; Pang, Shuping

    2014-11-01

    Nanopolyaniline coated graphene (GNP) was synthesized and flexible composite paper based on as-prepared GNP composite was fabricated by rolling process. Uniform PANI nanocoating prevents the graphene sheets from re-stacking during paper fabrication under high pressure. The composite paper was directly used as the supercapacitor without adding any binder and a specific capacitance of 255 F g-1 was achieved with high rate retention.

  8. Flexible dye solar cells

    Microsoft Academic Search

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

    2004-01-01

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

  9. Flexible responsive Janus nanosheets.

    PubMed

    Liu, Yijiang; Liang, Fuxin; Wang, Qian; Qu, Xiaozhong; Yang, Zhenzhong

    2015-02-28

    Flexible Janus nanosheets of molecular scale thickness (3.5 nm) are massively fabricated by a sol-gel process of a self-assembled monolayer of an amphiphilic silane onto a template. Groups of both sides are tuneable, and thus performance of the nanosheets, for example, is pH responsive. As a flexible solid emulsifier, the desired species can be wrapped with an individual nanosheet, which is pH triggered. PMID:25633051

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

    NASA Astrophysics Data System (ADS)

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

    1980-08-01

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

  11. Pavement texture from high-speed laser for pavement management system

    Microsoft Academic Search

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

    2012-01-01

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

  12. Modeling mechanistic responses in asphalt pavements under three-dimensional tire-pavement contact pressure

    Microsoft Academic Search

    Xiao-di Hu; L. F. Walubita

    2011-01-01

    A three dimensional finite element program incorporating actually measured vertical tire-pavement contact pressure (TPCP)\\u000a was utilized for modeling the mechanistic responses in asphalt concrete (AC) layers by simulating various vehicle motions:\\u000a stationary and non-stationary (i.e. in acceleration or deceleration mode). Analysis of the results indicated the following\\u000a items. 1) It is critical to use the vertical TPCP as the design

  13. 3-D Seismic Methods for Shallow Imaging Beneath Pavement

    E-print Network

    Miller, Brian

    2013-05-31

    The research presented in this dissertation focuses on survey design and acquisition of near-surface 3D seismic reflection and surface wave data on pavement. Increased efficiency for mapping simple subsurface interfaces through a combined use...

  14. Complex Modulus Prediction of Asphalt Concrete Pavement Cores 

    E-print Network

    Ling, Meng

    2013-12-02

    Complex modulus is one of the key parameters in the Mechanistic-Empirical Pavement Design Guide (MEPDG). The purpose of this study is to implement an accurate and high-efficiency mechanical method to measure and calculate the complex modulus...

  15. Deming Municipal Airport (DMN) Pavement Condition and Analysis

    E-print Network

    Cal, Mark P.

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

  16. Automated crack control analysis for concrete pavement construction 

    E-print Network

    Jang, Se Hoon

    2005-11-01

    The focus of this research is on the control of random cracking in concrete paving by using sawcut notch locations in the early stages of construction. This is a major concern in concrete pavement construction. This research also addresses a...

  17. Automated crack control analysis for concrete pavement construction

    E-print Network

    Jang, Se Hoon

    2005-11-01

    The focus of this research is on the control of random cracking in concrete paving by using sawcut notch locations in the early stages of construction. This is a major concern in concrete pavement construction. This research also addresses a...

  18. Nondestructive evaluation of load transfer at rigid airport pavement joints

    NASA Astrophysics Data System (ADS)

    Hammons, Michael I.

    1995-07-01

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

  19. Multi-period optimization of pavement management systems 

    E-print Network

    Yoo, Jaewook

    2004-09-30

    The purpose of this research is to develop a model and solution methodology for selecting and scheduling timely and cost-effective maintenance, rehabilitation, and reconstruction activities (M & R) for each pavement section ...

  20. Permeable Pavement Demonstration at the Edison Environmental Center - Poster

    EPA Science Inventory

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. Asphalt Pavement Surface Penetrate Rejuvenate Restore Technology: Application and Evaluation

    Microsoft Academic Search

    Xiaohong Guo; Bangyin Liu

    \\u000a This paper discussed the applicability of Asphalt Pavement Surface Penetrate Rejuvenation Restore Technology (SPRR) in preventive\\u000a maintenance, probed into the infiltration mechanism, rejuvenation mechanism, hermetic closure mechanism of micro-cracks, closed\\u000a pavement mechanism and bonding mechanism of discrete aggregate, and put forward the relevant construction technology and requirements\\u000a as well as its acceptance index. The actual case application has proved that

  3. Neural networks based concrete airfield pavement layer moduli backcalculation

    Microsoft Academic Search

    Halil Ceylan; Kasthurirangan Gopalakrishnan; M. Birkan Bayrak

    2008-01-01

    The Heavy Weight Deflectometer (HWD) is a Non-Destructive Test (NDT) equipment used to assess the structural condition of airfield pavement systems. This paper presents an Artificial Neural Networks (ANN) based approach for non-destructively estimating the stiffness properties of rigid airfield pavements subjected to full-scale dynamic traffic testing using simulated new generation aircraft gears. HWD tests were routinely conducted on three

  4. Preventive Maintenance Condition Standards of Expressway Asphalt Pavement

    Microsoft Academic Search

    Hu Guoxiang; Li Jie

    2009-01-01

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

  5. Fabrication of high performance Pt counter electrodes on conductive plastic substrate for flexible dye-sensitized solar cells

    Microsoft Academic Search

    Lili Chen; Weiwei Tan; Jingbo Zhang; Xiaowen Zhou; Xiaoling Zhang; Yuan Lin

    2010-01-01

    Pt counter electrodes (CEs) with different platinum loading have been prepared using chemical reduced method on flexible indium-doped tin oxide coated polyethylene naphthalate (ITO-PEN) for dye-sensitized solar cells (DSSCs). H2PtCl6·6H2O terpineol solutions were screen printed on the transparent ITO-PEN substrates. After drying, H2PtCl6 was reduced by treating it in NaBH4 solution followed by the hydrothermal treatment at 100°C. The obtained

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

    PubMed

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

    2013-05-30

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

  7. Facile synthesis of graphite/PEDOT/MnO2 composites on commercial supercapacitor separator membranes as flexible and high-performance supercapacitor electrodes.

    PubMed

    Tang, Pengyi; Han, Lijuan; Zhang, Li

    2014-07-01

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

  8. Effects of baseline levels of flexibility and vertical jump ability on performance following different volumes of static stretching and potentiating exercises in elite gymnasts.

    PubMed

    Donti, Olyvia; Tsolakis, Charilaos; Bogdanis, Gregory C

    2014-01-01

    This study examined the effects of baseline flexibility and vertical jump ability on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) following different volumes of stretching and potentiating exercises. ROM and CMJ were measured after two different warm-up protocols involving static stretching and potentiating exercises. Three groups of elite athletes (10 male, 14 female artistic gymnasts and 10 female rhythmic gymnasts) varying greatly in ROM and CMJ, performed two warm-up routines. One warm-up included short (15 s) static stretching followed by 5 tuck jumps, while the other included long static stretching (30 s) followed by 3x5 tuck jumps. ROM and CMJ were measured before, during and for 12 min after the two warm-up routines. Three-way ANOVA showed large differences between the three groups in baseline ROM and CMJ performance. A type of warm-up x time interaction was found for both ROM (p = 0.031) and CMJ (p = 0.016). However, all athletes, irrespective of group, responded in a similar fashion to the different warm-up protocols for both ROM and CMJ, as indicated from the lack of significant interactions for group (condition x group, time x group or condition x time x group). In the short warm-up protocol, ROM was not affected by stretching, while in the long warm-up protocol ROM increased by 5.9% ± 0.7% (p = 0.001) after stretching. Similarly, CMJ remained unchanged after the short warm-up protocol, but increased by 4.6 ± 0.9% (p = 0.012) 4 min after the long warm- up protocol, despite the increased ROM. It is concluded that the initial levels of flexibility and CMJ performance do not alter the responses of elite gymnasts to warm-up protocols differing in stretching and potentiating exercise volumes. Furthermore, 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance despite an increase in flexibility in these highly-trained athletes. Key PointsThe initial levels of flexibility and vertical jump ability have no effect on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) of elite gymnasts following warm-up protocols differing in stretching and potentiating exercise volumesStretching of the main leg muscle groups for only 15 s has no effect on ROM of elite gymnastsIn these highly-trained athletes, one set of 5 tuck jumps during warm-up is not adequate to increase CMJ performance, while 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance (by 4.6% above baseline), despite a 5.9% increase in flexibility due to the 30 s stretching exercises. PMID:24570613

  9. Flexible-textured polydimethylsiloxane antireflection structure for enhancing omnidirectional photovoltaic performance of Cu(In,Ga)Se2 solar cells.

    PubMed

    Kuo, Shou-Yi; Hsieh, Ming-Yang; Han, Hau-Vei; Lai, Fang-I; Chuang, Tsung-Yeh; Yu, Peichen; Lin, Chien-Chung; Kuo, Hao-Chung

    2014-02-10

    Because of the Sun's movement across the sky, broadband and omnidirectional light harvesting is a major development in photovoltaic technology. This study reports the fabrication and characterization of flexible-textured polydimethylsiloxane (PDMS) film on Cu(In,Ga)Se2 (CIGS) solar cells, which is one of the simplest and cheapest peel-off processes for fabricating a three-dimensional structure. A cell containing a textured PDMS film enhanced the short-circuit current density from 22.12 to 23.93 mA/cm2 in a simulated one-sun scenario. The omnidirectional antireflection of CIGS solar cells containing various PDMS films is also investigated. This study uses an angle-resolved reflectance spectroscope to investigate the omnidirectional and broadband optical properties of the proposed PDMS film. This improvement in light harvesting is attributable to the scattering of the PDMS film and the gradual refractive index profile between the PDMS microstructures and air. The flexible-textured PDMS film is suitable for creating an antireflective coating for a diverse range of photovoltaic devices. PMID:24663578

  10. Deconstructing a Plant Macromolecular Assembly: Chemical Architecture, Molecular Flexibility, And Mechanical Performance of Natural and Engineered Potato Suberins

    PubMed Central

    2015-01-01

    Periderms present in plant barks are essential protective barriers to water diffusion, mechanical breakdown, and pathogenic invasion. They consist of densely packed layers of dead cells with cell walls that are embedded with suberin. Understanding the interplay of molecular structure, dynamics, and biomechanics in these cell wall-associated insoluble amorphous polymeric assemblies presents substantial investigative challenges. We report solid-state NMR coordinated with FT-IR and tensile strength measurements for periderms from native and wound-healing potatoes and from potatoes with genetically modified suberins. The analyses include the intact suberin aromatic–aliphatic polymer and cell-wall polysaccharides, previously reported soluble depolymerized transmethylation products, and undegraded residues including suberan. Wound-healing suberized potato cell walls, which are 2 orders of magnitude more permeable to water than native periderms, display a strikingly enhanced hydrophilic–hydrophobic balance, a degradation-resistant aromatic domain, and flexibility suggestive of an altered supramolecular organization in the periderm. Suppression of ferulate ester formation in suberin and associated wax remodels the periderm with more flexible aliphatic chains and abundant aromatic constituents that can resist transesterification, attenuates cooperative hydroxyfatty acid motions, and produces a mechanically compromised and highly water-permeable periderm. PMID:24502663

  11. High performance flexible top-emitting warm-white organic light-emitting devices and chromaticity shift mechanism

    NASA Astrophysics Data System (ADS)

    Shi, Hongying; Deng, Lingling; Chen, Shufen; Xu, Ying; Zhao, Xiaofei; Cheng, Fan; Huang, Wei

    2014-04-01

    Flexible warm-white top-emitting organic light-emitting devices (TEOLEDs) are fabricated onto PET substrates with a simple semi-transparent cathode Sm/Ag and two-color phosphors respectively doped into a single host material TCTA. By adjusting the relative position of the orange-red EML sandwiched between the blue emitting layers, the optimized device exhibits the highest power/current efficiency of 8.07 lm/W and near 13 cd/A, with a correlated color temperature (CCT) of 4105 K and a color rendering index (CRI) of 70. In addition, a moderate chromaticity variation of (-0.025, +0.008) around warm white illumination coordinates (0.45, 0.44) is obtained over a large luminance range of 1000 to 10000 cd/m2. The emission mechanism is discussed via delta-doping method and single-carrier device, which is summarized that the carrier trapping, the exciton quenching, the mobility change and the recombination zone alteration are negative to color stability while the energy transfer process and the blue/red/blue sandwiched structure are contributed to the color stability in our flexible white TEOLEDs.

  12. High performance flexible top-emitting warm-white organic light-emitting devices and chromaticity shift mechanism

    SciTech Connect

    Shi, Hongying; Deng, Lingling; Chen, Shufen, E-mail: iamsfchen@njupt.edu.cn, E-mail: wei-huang@njupt.edu.cn; Xu, Ying; Zhao, Xiaofei; Cheng, Fan [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China)] [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China); Huang, Wei, E-mail: iamsfchen@njupt.edu.cn, E-mail: wei-huang@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China) [Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 210023 Nanjing (China); Jiangsu-Singapore Joint Research Center for Organic/Bio- Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Technology, Nanjing 211816 (China)

    2014-04-15

    Flexible warm-white top-emitting organic light-emitting devices (TEOLEDs) are fabricated onto PET substrates with a simple semi-transparent cathode Sm/Ag and two-color phosphors respectively doped into a single host material TCTA. By adjusting the relative position of the orange-red EML sandwiched between the blue emitting layers, the optimized device exhibits the highest power/current efficiency of 8.07 lm/W and near 13 cd/A, with a correlated color temperature (CCT) of 4105 K and a color rendering index (CRI) of 70. In addition, a moderate chromaticity variation of (-0.025, +0.008) around warm white illumination coordinates (0.45, 0.44) is obtained over a large luminance range of 1000 to 10000 cd/m{sup 2}. The emission mechanism is discussed via delta-doping method and single-carrier device, which is summarized that the carrier trapping, the exciton quenching, the mobility change and the recombination zone alteration are negative to color stability while the energy transfer process and the blue/red/blue sandwiched structure are contributed to the color stability in our flexible white TEOLEDs.

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

    PubMed Central

    Tsolakis, Charilaos; Bogdanis, Gregory C.

    2012-01-01

    This study examined the effects of two different warm-up protocols on lower limb power and flexibility in high level athletes. Twenty international level fencers (10 males and 10 females) performed two warm-up protocols that included 5-min light jogging and either short (15s) or long (45s) static stretching exercises for each of the main leg muscle groups (quadriceps, hamstrings and triceps surae), followed by either 3 sets of 3 (short stretching treatment), or 3 sets of 5 tuck jumps (long stretching treatment), in a randomized crossover design with one week between treatments. Hip joint flexion was measured with a Lafayette goniometer before and after the 5-min warm-up, after stretching and 8 min after the tuck jumps, while counter movement jump (CMJ) performance was evaluated by an Ergojump contact platform, before and after the stretching treatment, as well as immediately after and 8 minutes after the tuck jumps. Three way ANOVA (condition, time, gender) revealed significant time (p < 0.001) and gender (p < 0.001) main effects for hip joint flexion, with no interaction between factors. Flexibility increased by 6. 8 ± 1.1% (p < 0.01) after warm-up and by another 5.8 ± 1.6% (p < 0.01) after stretching, while it remained increased 8 min after the tuck jumps. Women had greater ROM compared with men at all time points (125 ± 8° vs. 94 ± 4° p<0.01 at baseline), but the pattern of change in hip flexibility was not different between genders. CMJ performance was greater in men compared with women at all time points (38.2 ± 1.9 cm vs. 29.8 ± 1.2 cm p < 0.01 at baseline), but the percentage of change CMJ performance was not different between genders. CMJ performance remained unchanged throughout the short stretching protocol, while it decreased by 5.5 ± 0.9% (p < 0.01) after stretching in the long stretching protocol However, 8 min after the tuck jumps, CMJ performance was not different from the baseline value (p = 0.075). In conclusion, lower limb power may be decreased after long periods of stretching, but performance of explosive exercises may reverse this phenomenon. Key points Stretching of the main leg muscle groups for 45 s results in a relatively large decrease (by 5.5%) in subsequent jumping performance Stretching of the main leg muscle groups for only 15 s results in an increase in flexibility similar to that of the longer duration stretching (by 12.6%), with no change in subsequent jumping performance Performance of a PAP exercise such as tuck jumps may reverse the negative effects of long duration stretching on leg muscle power. However, jumping performance is not increased above baseline Speed/power athletes should be advised against using long duration stretching. The number of repetitions of a PAP exercise such as the tuck jumps, should be further examined in order to induce an increase in explosive performance during competition PMID:24150077

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

    MedlinePLUS

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

  15. Determination of the Presence Conditions of Pavement Markings using Image Processing

    E-print Network

    Ge, Hancheng

    2012-10-19

    Pavement markings, as a form of traffic control devices, play a crucial role in safely guiding drivers. Restriping pavement markings is an important task in the maintenance of traffic control devices. Every year state agencies spend a lot of money...

  16. Permanent Deformation of Asphalt Concrete Pavements: A Nonlinear Viscoelastic Approach to Mix Analyses and Design

    E-print Network

    Long, Fenella Margare

    2001-01-01

    model. 34 3.1.1 Mix Design: The asphalt concrete mix used inConcrete Pavements: A Nonlinear Viscoelastic Approach to Mix Analyses and DesignConcrete Pavements: A Nonlinear Viscoelastic Approach to Mix Analyses and Design

  17. POROUS PAVEMENT PHASE I DESIGN AND OPERATIONAL CRITERIA (EPA/600/2-80/135)

    EPA Science Inventory

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

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

    E-print Network

    Menendez Acurio, Jose Rafael

    2014-07-30

    management systems must be upgraded to incorporate risk management, permitting pavement management systems to serve as a more realistic decision support tool for planning and budget allocation in pavement maintenance and rehabilitation. This dissertation...

  19. Characterization of cementitiously stabilized subgrades for mechanistic-empirical pavement design

    NASA Astrophysics Data System (ADS)

    Solanki, Pranshoo

    Pavements are vulnerable to subgrade layer performance because it acts as a foundation. Due to increase in the truck traffic, pavement engineers are challenged to build more strong and long-lasting pavements. To increase the load-bearing capacity of pavements, subgrade layer is often stabilized with cementitious additives. Thus, an overall characterization of stabilized subgrade layer is important for enhanced short- and long-term pavement performance. In this study, the effect of type and amount of additive on the short-term performance in terms of material properties recommended by the new Mechanistic-Empirical Pavement Design Guide (MEPDG) is examined. A total of four soils commonly encountered as subgrades in Oklahoma are utilized. Results show that the changes in the Mr, ME and UCS values stabilized specimens depend on the soil type and properties of additives. The long-term performance (or durability) of stabilized soil specimens is investigated by conducting freeze-thaw (F-T) cycling, vacuum saturation and tube suction tests on 7-day cured P-, K- and C-soil specimens stabilized with 6% lime, 10% CFA and 10% CKD. This study is motivated by the fact that during the service life of pavement stabilized layers are subjected to F-T cycles and moisture variations. It is found that that UCS value of all the stabilized specimens decreased with increase in the number of F-T cycles. A strong correlation was observed between UCS values retained after vacuum saturation and F-T cycles indicating that vacuum saturation could be used as a time-efficient and inexpensive method for evaluating durability of stabilized soils. In this study, short- and long-term observations from stabilization of sulfate bearing soil with locally available low (CFA), moderate (CKD) and high (lime) calcium-based stabilizers are determined to evaluate and compare the effect of additive type on the phenomenon of sulfate-induced heave. The impact of different factors on the development of the ettringite, responsible for sulfate-induced heaving, is also discussed. For Level 2 design of pavements, a total of four stress-based statistical models and two feed-forward-type artificial neural network (ANN) models, are evaluated for predicting resilient modulus of 28-day cured stabilized specimens. Specifically, one semi-log stress-based, three log-log stress-based, one Multi-Layer Perceptrons Network (MLPN), and one Radial Basis Function Network (RBFN) are developed. Overall, semi-log stress-based and MLPN neural network are found to show best acceptable performance for the present evaluation and validation datasets. Further, correlations are presented for stress-based models to correlate Mr with compacted specimen characteristics and soil/additive properties. Additionally, the effect of type of additive on indirect tensile and fatigue characteristics of selected stabilized P- and V-soil is evaluated. This study is based on the fact that stabilized layer is subjected to tensile stresses under wheel loading. Thus, the resilient modulus in tension (M rt), fatigue life and strength in tension (sigmat) or flexure (represented by modulus of rupture, MOR) becomes another important design parameter within the mechanistic framework. Cylindrical specimens are prepared, cured for 28 days and subjected to different stress sequences in indirect tension to study the Mrt. On the other hand, stabilized beam specimens are compacted using a Linear Kneading Compactor and subjected to repeated cycles of reloading-unloading after 28 days of curing in a four-point beam fatigue apparatus for evaluating fatigue life and flexural stiffness. It is found that all three additives improved the Mrt, sigmat and MOR values; however, degree of improvement varied with the type of additive and soil. This study encompasses the differences in the design of semi-rigid pavements developed using AASHTO 1993 and AASHTO 2002 MEPDG methodologies. Further, the design curves for fatigue performance prediction of stabilized layers are developed for different stabilized pavement sections. Knowledge gained f

  20. On-site inspections of pavement damages evolution using GPR

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Ground-penetrating radar (GPR) is being increasingly used for pavements maintenance due to the wide range of applications spanning from physical to geometrical inspections, thereby allowing for a reliable diagnosis of the main causes of road structural damages. In this work, an off-ground GPR system was used to investigate a large-scale rural road network. Two sets of surveys were carried out in different time periods, with the main goals to i) localize the most critical sections; ii) monitor the evolution of previous damages and localize newborn deep faults, although not revealed at the pavement surface level; iii) analyze the causes of both evolution and emergence of faults by considering environmental and human factors. A 1-GHz GPR air-launched antenna was linked to an instrumented van for collecting data at traffic speed. Other support techniques (e.g. GPS data logger, odometer, HD video camera) were used for cross-checking,. Such centre frequency of investigation along with a 25-ns time window allow for a signal penetration of 900 mm, consistent with the deepest layer interfaces. The bottom of the array was 400 mm over the surface, with a minimum distance of 1200 mm from the van body. Scan length of maximum 10 km were provided for avoiding heavy computational loads. The rural road network was located in the District of Rieti, 100 km north from Rome, Italy, and mostly develops in a hilly and mountainous landscape. In most of the investigated roads, the carriageway consists in two lanes of 3.75 meters wide and two shoulders of 0.50 meters wide. A typical road section includes a HMA layer (65 mm average thickness), a base layer (100 mm average thickness), and a subbase layer (300 mm average thickness), as described by pavement design charts. The first set of surveys was carried out in two days at the beginning of spring in moderately dry conditions. Overall, 320-km-long inspections were performed in both travel directions, thereby showing a productivity of approximately 160 km/day at 40 km/h speed, on the average. After processing and first-checking, GPR profiles were divided into homogeneous sections according to the combination of different parameters (e.g. route analyzed, long distance conditions of regularity/irregularity in layers arrangement). In such context, a high consistency between surface damages, mismatches from the GPR scans, and boundary environmental conditions was demonstrated. In addition, deep mismatches were detected even for early-stage or unrevealed faults. The second set of surveys was carried out in autumn in high humidity conditions, due to recent rainfalls. 160 km of relevant routes from the same road network were investigated. Results showed a high consistency with those collected during the first-stage of surveys. Minor changes were found in those sections with low traffic loads (e.g. farther away from the biggest town of Rieti), whereas major mismatches were detected in wetlands (e.g. close to rivers), work zones, and nearby those sections already deeply damaged in the past. This work benefited from networking activities carried out within the EU funded COST Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar'.

  1. Experimental studies of the dilution of vehicle exhaust pollutants by environment-protecting pervious pavement

    Microsoft Academic Search

    Chung-Ming Liu; Jui-Wen Chen; Jen-Hui Tsai; Wei-Shian Lin; M.-T. Yen; Ting-Hao Chen

    2012-01-01

    This study determines whether environment-protecting pervious pavement can dilute pollutants immediately after emissions from vehicle. The turbulence-driven dry-deposition process is too slow to be considered in this aspect. The pavement used is the JW pavement (according to its inventor's name), a high-load-bearing water-permeable pavement with patents in over 100 countries, which has already been used for more than 8 years

  2. Perfusion-Style Semi-rigid Pavement Design and Construction of Materials

    Microsoft Academic Search

    Li Hongzhi; Zheng Jianlong

    2010-01-01

    As the semi-rigid asphalt pavement rutting and so prone to disease and cement road surface is due to a large number of joints affected by driving comfort, so open-graded asphalt gravel infusion epoxy resin modified cement mortar to form a semi-rigid asphalt pavement can be overcome pavement and cement pavement deficiencies. This article describes the perfusion of the material composition

  3. Harvesting energy from asphalt pavements and reducing the heat island effect

    Microsoft Academic Search

    Rajib B. Mallick; Bao-Liang Chen; Sankha Bhowmick

    2009-01-01

    A rise in temperature of asphalt pavements contributes towards the urban heat island effect, causes problems with air quality and increases the power requirement for cooling buildings. A high temperature would also lead to the potential of rutting failure in asphalt pavements. The concept of mining heat from asphalt pavements, utilising an appropriate fluid flowing in pipes installed within the

  4. National Concrete PavementTechnology Center 2711 South Loop Drive, Suite 4700

    E-print Network

    National Concrete PavementTechnology Center 2711 South Loop Drive, Suite 4700 Ames, IA 50010, National Concrete Pavement Technology Center, Iowa State University Co-Principal Investigators Theodore Group, Inc. Project Manager Paul Wiegand Research Engineer, National Concrete Pavement Technology Center

  5. Thermal conductance of and heat generation in tire-pavement interface and effect on aircraft braking

    NASA Technical Reports Server (NTRS)

    Miller, C. D.

    1976-01-01

    A finite-difference analysis was performed on temperature records obtained from a free rolling automotive tire and from pavement surface. A high thermal contact conductance between tire and asphalt was found on a statistical basis. Average slip due to squirming between tire and asphalt was about 1.5 mm. Consequent friction heat was estimated as 64 percent of total power absorbed by bias-ply, belted tire. Extrapolation of results to aircraft tire indicates potential braking improvement by even moderate increase of heat absorbing capacity of runway surface.

  6. Urban evaporation rates for water-permeable pavements.

    PubMed

    Starke, P; Göbel, P; Coldewey, W G

    2010-01-01

    In urban areas the natural water balance is disturbed. Infiltration and evaporation are reduced, resulting in a high surface runoff and a typical city climate, which can lead to floods and damages. Water-permeable pavements have a high infiltration rate that reduces surface runoff by increasing the groundwater recharge. The high water retention capacity of the street body of up to 51 l/m(2) and its connection via pores to the surface lead to higher evaporation rates than impermeable surfaces. A comparison of these two kinds of pavements shows a 16% increase in evaporation levels of water-permeable pavements. Furthermore, the evaporation from impermeable pavements is linked directly to rain events due to fast-drying surfaces. Water-permeable pavements show a more evenly distributed evaporation after a rain event. Cooling effects by evaporative heat loss can improve the city climate even several days after rain events. On a large scale use, uncomfortable weather like sultriness or dry heat can be prevented and the urban water balance can be attenuated towards the natural. PMID:20818060

  7. Flexible nanovectors

    Microsoft Academic Search

    Nicola M. Pugno

    2008-01-01

    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

  8. Lightweight and flexible reduced graphene oxide/water-borne polyurethane composites with high electrical conductivity and excellent electromagnetic interference shielding performance.

    PubMed

    Hsiao, Sheng-Tsung; Ma, Chen-Chi M; Liao, Wei-Hao; Wang, Yu-Sheng; Li, Shin-Ming; Huang, Yu-Chin; Yang, Ruey-Bin; Liang, Wen-Fan

    2014-07-01

    In this study, we developed a simple and powerful method to fabricate flexible and lightweight graphene-based composites that provide high electromagnetic interference (EMI) shielding performance. Electrospun waterborne polyurethane (WPU) that featured sulfonate functional groups was used as the polymer matrix, which was light and flexible. First, graphene oxide (GO)/WPU composites were prepared through layer-by-layer (L-b-L) assembly of two oppositely charged suspensions of GO, the cationic surfactant (didodecyldimethylammonium bromide, DDAB)-adsorbed GO and intrinsic negatively charged GO, depositing on the negatively charged WPU fibers. After the L-b-L assembly cycles, the GO bilayers wrapped the WPU fiber matrix completely and revealed fine connections guided by the electrospun WPU fibers. Then, we used hydroiodic acid (HI) to obtain highly reduced GO (r-GO)/WPU composites, which exhibited substantially enhanced electrical conductivity (approximately 16.8 S/m) and, moreover, showed a high EMI-shielding effectiveness (approximately 34 dB) over the frequency range from 8.2 to 12.4 GHz. PMID:24921939

  9. High-performance flexible Ag nanowire electrode with low-temperature atomic-layer-deposition fabrication of conductive-bridging ZnO film

    NASA Astrophysics Data System (ADS)

    Duan, Ya-Hui; Duan, Yu; Chen, Ping; Tao, Ye; Yang, Yong-Qiang; Zhao, Yi

    2015-02-01

    As material for flexible transparent electrodes for organic photoelectric devices, the silver nanowires (AgNWs) have been widely studied. In this work, we propose a hybrid flexible anode with photopolymer substrate, which is composed of spin-coating-processed AgNW meshes and of zinc oxide (ZnO) prepared by low-temperature (60°C) atomic layer deposition. ZnO effectively fills in the voids of the AgNW mesh electrode, which is thus able to contact to the device all over the active area, to allow for efficient charge extraction/injection. Furthermore, ZnO grown by low temperature mainly relies on hole conduction to make the anode play a better role. Hole-only devices are fabricated to certify the functionality of the low-temperature ZnO film. Finally, we confirm that the ZnO film grown at a low temperature bring a significant contribution to the performance of the modified AgNW anode.

  10. High-performance flexible Ag nanowire electrode with low-temperature atomic-layer-deposition fabrication of conductive-bridging ZnO film.

    PubMed

    Duan, Ya-Hui; Duan, Yu; Chen, Ping; Tao, Ye; Yang, Yong-Qiang; Zhao, Yi

    2015-01-01

    As material for flexible transparent electrodes for organic photoelectric devices, the silver nanowires (AgNWs) have been widely studied. In this work, we propose a hybrid flexible anode with photopolymer substrate, which is composed of spin-coating-processed AgNW meshes and of zinc oxide (ZnO) prepared by low-temperature (60°C) atomic layer deposition. ZnO effectively fills in the voids of the AgNW mesh electrode, which is thus able to contact to the device all over the active area, to allow for efficient charge extraction/injection. Furthermore, ZnO grown by low temperature mainly relies on hole conduction to make the anode play a better role. Hole-only devices are fabricated to certify the functionality of the low-temperature ZnO film. Finally, we confirm that the ZnO film grown at a low temperature bring a significant contribution to the performance of the modified AgNW anode. PMID:25852386

  11. Analyses to improve operational flexibility

    Microsoft Academic Search

    Trikouros

    1986-01-01

    Operational flexibility is greatly enhanced if the technical bases for plant limits and design margins are fully understood, and the analyses necessary to evaluate the effect of plant modifications or changes in operating modes on these parameters can be performed as required. If a condition should arise that might jeopardize a plant limit or reduce operational flexibility, it would be

  12. Design and implementation of PAVEMON: A GIS web-based pavement monitoring system based on large amounts of heterogeneous sensors data

    NASA Astrophysics Data System (ADS)

    Shahini Shamsabadi, Salar

    A web-based PAVEment MONitoring system, PAVEMON, is a GIS oriented platform for accommodating, representing, and leveraging data from a multi-modal mobile sensor system. Stated sensor system consists of acoustic, optical, electromagnetic, and GPS sensors and is capable of producing as much as 1 Terabyte of data per day. Multi-channel raw sensor data (microphone, accelerometer, tire pressure sensor, video) and processed results (road profile, crack density, international roughness index, micro texture depth, etc.) are outputs of this sensor system. By correlating the sensor measurements and positioning data collected in tight time synchronization, PAVEMON attaches a spatial component to all the datasets. These spatially indexed outputs are placed into an Oracle database which integrates seamlessly with PAVEMON's web-based system. The web-based system of PAVEMON consists of two major modules: 1) a GIS module for visualizing and spatial analysis of pavement condition information layers, and 2) a decision-support module for managing maintenance and repair (M?) activities and predicting future budget needs. PAVEMON weaves together sensor data with third-party climate and traffic information from the National Oceanic and Atmospheric Administration (NOAA) and Long Term Pavement Performance (LTPP) databases for an organized data driven approach to conduct pavement management activities. PAVEMON deals with heterogeneous and redundant observations by fusing them for jointly-derived higher-confidence results. A prominent example of the fusion algorithms developed within PAVEMON is a data fusion algorithm used for estimating the overall pavement conditions in terms of ASTM's Pavement Condition Index (PCI). PAVEMON predicts PCI by undertaking a statistical fusion approach and selecting a subset of all the sensor measurements. Other fusion algorithms include noise-removal algorithms to remove false negatives in the sensor data in addition to fusion algorithms developed for identifying features on the road. PAVEMON offers an ideal research and monitoring platform for rapid, intelligent and comprehensive evaluation of tomorrow's transportation infrastructure based on up-to-date data from heterogeneous sensor systems.

  13. Asphalt additives in thick hot mixed asphalt-concrete pavements. Research report (Interim), Sep 86-Oct 90

    SciTech Connect

    Button, J.W.; Prapnnachari, S.

    1991-01-01

    Asphalt concrete field test pavements were placed in District 19 north of Texarkana on US-59/71 in 1987 and 1988 to evaluate the ability of certain asphalt additives to enhance resistance to cracking and rutting. Two 10-inch thick and 0.9 mile (approx.) long test pavements and a similar untreated control section were constructed in the northbound and southbound lanes for a total of 6 field trials. Asphalt additives were incorporated in both the 8-inch base and the overlying 2-inch surface layers. The additives evaluated included Goodyear LPF 5812, Chemkrete-CTI 102, Exxon Polybilt 102, and Styrelf 13. Samples of paving materials including aggregates, asphalts, compacted mixes, and pavement cores were collected, conveyed to the laboratory, and tested to provide detailed documentation of their properties. Tests included rheological properties of the binders before and after artificial aging, characterization of aggregate, Hveem and Marshall stability, stiffness as a function of temperature, tensile properties before and after moisture conditioning and artificial aging, air void content, creep, and permanent deformation. Field tests and visual evaluations have been conducted to objectively evaluate field performance. Results of these tests are reported herein. Within 6 months after construction of the base layers and prior to placement of the surface course, the Chemkrete modified base became severely cracked. As a result, the surface mix placed on this base section was treated with Goodyear latex rather than Chemkrete. All other modified pavements and the control section have performed well and exhibited essentially equivalent performance after 2 1/2 years in service.

  14. Performance of gas-lubricated nonconforming pivoted-pad journal bearings and a flexibly mounted spiral-groove thrust bearing

    NASA Technical Reports Server (NTRS)

    Ream, L. W.

    1973-01-01

    A test program was conducted to determine the performance characteristics of gas-lubricated nonconforming pivoted-pad journal bearings and a spiral-groove thrust bearing designed for the Brayton cycle rotating unit (BRU). Hydrostatic, hybrid (simultaneously hydrostatic and hydrodynamic), and hydrodynamic tests were conducted in argon gas at ambient pressure and temperature ranges representative of hydrostatic operation up to the 10.5-kWe BRU power-generating level. Performance of the gas lubricated bearings is presented, including hydrostatic gas flow rates, bearing clearances, bearing temperatures, and transient performance.

  15. Design prediction of pavement skid resistance from laboratory tests

    NASA Astrophysics Data System (ADS)

    Parcells, W. H.; Metheny, T. M.; Maag, R. G.

    1980-08-01

    Methods for preevaluating aggregates and paving mixtures so that predictions can be made covering skid resistance properties of proposed and in service pavement types are discussed. A correlation was established between the field testing using the data from the British Portable Tester and the Locked Wheel Pavement Friction Trailer at speeds of 40 and 55 mph. Core samples were extracted from the Locked Wheel Tester Skid Path and subjected to wear on the small wheel circular track with periodic surface friction testing. The final step was to remix and remold the cored pavement samples or make samples with new materials to obtain an 'as new' surface and again subject these samples to wear on the small wheel circular track with periodic testing.

  16. Surface wave attenuation measurement for application to pavement characterization

    NASA Astrophysics Data System (ADS)

    Popovics, John S.; Song, Won-Joon; Achenbach, Jan D.

    1998-03-01

    There is a need for non-destructive evaluation (NDE) techniques which can effectively determine the extent of damage (cracking) in concrete structures. Non-destructive, one-sided surface wave attenuation measurement is a very sensitive and practical tool for such characterization. A technique for practical determination of frequency-dependent surface wave attenuation is introduced and demonstrated to be sensitive to damage in free concrete slabs. A theoretical model for the attenuation response in undamaged free slabs is introduced and shown to accurately predict experimentally obtained responses in concrete within certain frequency limits. The theoretical model is then used to investigate the practical application of the attenuation technique to concrete pavement NDE in terms of slab depth and subbase conditions. Theoretically obtained data are presented for a variety of pavement types. Based on the presented results of the theoretical model, conclusions concerning practical application of the technique to pavement inspection are given.

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

    Microsoft Academic Search

    John MacDuffie

    1995-01-01

    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 \\

  18. Vibration of vehicle-pavement coupled system based on a Timoshenko beam on a nonlinear foundation

    NASA Astrophysics Data System (ADS)

    Ding, Hu; Yang, Yan; Chen, Li-Qun; Yang, Shao-Pu

    2014-12-01

    This paper focuses on the coupled nonlinear vibration of vehicle-pavement system. The pavement is modeled as a Timoshenko beam resting on a six-parameter foundation. The vehicle is simplified as a spring-mass-damper oscillator. For the first time, the dynamic response of vehicle-pavement coupled system is studied by modeling the pavement as a Timoshenko beam resting on a nonlinear foundation. Consequently, the shear effects and the rotational inertia of the pavement are included in the modeling process. The pavement model is assumed to be a linear-plus-cubic Pasternak-type foundation. Furthermore, the convergent Galerkin truncation is used to obtain approximate solutions to the coupled vibratory response of the vehicle-pavement coupled system. The dynamic responses of the vehicle-pavement system with the asphalt pavement on soft soil foundation are investigated via the numerical examples. The numerical results show that the calculation for the coupled vibratory response needs high-order modes. Moreover, the coupling effects between the pavement and the vehicle are numerically examined by using the convergent modal truncation. The physical parameters of the vehicle-pavement system such as the shear modulus are compared for determining their influences on the coupled vibratory response.

  19. The use of fluvial and marine sediments in the formulation of roller compacted concrete for use in pavements.

    PubMed

    Zdiri, M; Abriakb, N E; Ben Ouezdoua, M; Neji, J

    2009-07-01

    In the manufacture of Roller Compacted Concrete (RCC) used for pavement materials, various types of aggregates are used, such as crushed and rolled limestone or siliceous aggregates. The main objective is always to reach the maximum compactness to achieve higher mechanical performances. In the present work, fluvial and marine sediments, resulting from the dredging of harbours and rivers, were introduced as aggregates in the preparation of RCC for pavement construction, with a view to improving the mechanical strength of the RCC. This study included a granulometric, mineralogical and chemical characterization of the aggregates. The work also contains a mechanical characterization of the resulting material. The objective of the study was to find a resistant RCC, by developing materials such as sediments that are often classified as a waste and where their storage is harmful to the environment. The mechanical strengths obtained showed the profitability of using a Roller Compacted Concrete containing sediments. PMID:19705664

  20. An algorithm for pavement crack detection based on multiscale space

    NASA Astrophysics Data System (ADS)

    Liu, Xiang-long; Li, Qing-quan

    2006-10-01

    Conventional human-visual and manual field pavement crack detection method and approaches are very costly, time-consuming, dangerous, labor-intensive and subjective. They possess various drawbacks such as having a high degree of variability of the measure results, being unable to provide meaningful quantitative information and almost always leading to inconsistencies in crack details over space and across evaluation, and with long-periodic measurement. With the development of the public transportation and the growth of the Material Flow System, the conventional method can far from meet the demands of it, thereby, the automatic pavement state data gathering and data analyzing system come to the focus of the vocation's attention, and developments in computer technology, digital image acquisition, image processing and multi-sensors technology made the system possible, but the complexity of the image processing always made the data processing and data analyzing come to the bottle-neck of the whole system. According to the above description, a robust and high-efficient parallel pavement crack detection algorithm based on Multi-Scale Space is proposed in this paper. The proposed method is based on the facts that: (1) the crack pixels in pavement images are darker than their surroundings and continuous; (2) the threshold values of gray-level pavement images are strongly related with the mean value and standard deviation of the pixel-grey intensities. The Multi-Scale Space method is used to improve the data processing speed and minimize the effectiveness caused by image noise. Experiment results demonstrate that the advantages are remarkable: (1) it can correctly discover tiny cracks, even from very noise pavement image; (2) the efficiency and accuracy of the proposed algorithm are superior; (3) its application-dependent nature can simplify the design of the entire system.

  1. One step grafting of iron phthalocyanine containing flexible chains on Fe3O4 nanoparticles towards high performance polymer magnetic composites

    NASA Astrophysics Data System (ADS)

    Pu, Zejun; Zhou, Xuefei; Yang, Xulin; Jia, Kun; Liu, Xiaobo

    2015-07-01

    To develop high-performance inorganic particles/polymer composites, the interfacial interaction and dispersion of inorganic particles are the two essential issues to be considered. Herein, we report an effective approach to graft iron phthalocyanine containing flexible chains (NP-ph) on Fe3O4 nanoparticles (NP-ph@Fe3O4). The hybrids were monodispersed solid nanoparticles with the average diameter of about 250 nm. About 16.8% of the phthalocyanine oligomer was incorporated into the resulting NP-ph@Fe3O4 nanoparticles. The NP-ph@Fe3O4 nanoparticles were subsequently used as the novel filler for preparation of high performance poly(arylene ether nitrile)s (PAEN) composites. The scanning electron microscopy (SEM) investigation showed that the NP-ph@Fe3O4 nanoparticles present better dispersion and interfacial compatibility with PAEN matrix than that of raw Fe3O4, which was further confirmed by rheological study. Consequently, the improved thermal stability and enhanced mechanical properties were obtained from composites using NP-ph@Fe3O4. Vibrating sample magnetometer (VSM) results showed that the prepared PAEN composites exhibited higher saturation magnetization and soft magnetic properties. Meanwhile, the saturation magnetization (Ms) of the PAEN/NP-ph@Fe3O4 composite films increased with the increase of the hybrid nanoparticles loading. Thus, the PAEN/NP-ph@Fe3O4 composite would find potential applications in organic magnetic films fields due to their high thermal stability, excellent flexibility and tunable magnetic properties

  2. Some advances/results in monitoring road cracks from 2D pavement images within the scope of the collaborative FP7 TRIMM project

    NASA Astrophysics Data System (ADS)

    Baltazart, Vincent; Moliard, Jean-Marc; Amhaz, Rabih; Wright, Dean; Jethwa, Manish

    2015-04-01

    Monitoring road surface conditions is an important issue in many countries. Several projects have looked into this issue in recent years, including TRIMM 2011-2014. The objective of such projects has been to detect surface distresses, like cracking, raveling and water ponding, in order to plan effective road maintenance and to afford a better sustainability of the pavement. The monitoring of cracking conventionally focuses on open cracks on the surface of the pavement, as opposed to reflexive cracks embedded in the pavement materials. For monitoring surface condition, in situ human visual inspection has been gradually replaced by automatic image data collection at traffic speed. Off-line image processing techniques have been developed for monitoring surface condition in support of human visual control. Full automation of crack monitoring has been approached with caution, and depends on a proper manual assessment of the performance. This work firstly presents some aspects of the current state of monitoring that have been reported so far in the literature and in previous projects: imaging technology and image processing techniques. Then, the work presents the two image processing techniques that have been developed within the scope of the TRIMM project to automatically detect pavement cracking from images. The first technique is a heuristic approach (HA) based on the search for gradient within the image. It was originally developed to process pavement images from the French imaging device, Aigle-RN. The second technique, the Minimal Path Selection (MPS) method, has been developed within an ongoing PhD work at IFSTTAR. The proposed new technique provides a fine and accurate segmentation of the crack pattern along with the estimation of the crack width. HA has been assessed against the field data collection provided by Yotta and TRL with the imaging device Tempest 2. The performance assessment has been threefold: first it was performed against the reference data set including 130 km of pavement images over UK roads, second over a few selected short sections of contiguous pavement images, and finally over a few sample images as a case study. The performance of MPS has been assessed against an older image data base. Pixel-based PGT was available to provide the most sensitive performance assessment. MPS has shown its ability to provide a very accurate cracking pattern without reducing the image resolution on the segmented images. Thus, it allows measurement of the crack width; it is found to behave more robustly against the image texture and better matched for dealing with low contrast pavement images. The benchmarking of seven automatic segmentation techniques has been provided at both the pixel and the grid levels. The performance assessment includes three minimal path selection algorithms, namely MPS, Free Form Anisotropy (FFA), one geodesic contour with automatic selection of points of interests (GC-POI), HA, and two Markov-based methods. Among others, MPS approach reached the best performance at the pixel level while it is matched to the FFA approach at the grid level. Finally, the project has emphasized the need for a reliable ground truth data collection. Owing to its accuracy, MPS may serve as a reference benchmark for other methods to provide the automatic segmentation of pavement images at the pixel level and beyond. As a counterpart, MPS requires a reduction in the computing time. Keywords: cracking, automatic segmentation, image processing, pavement, surface distress, monitoring, DICE, performance

  3. Evaluation of multilayered pavement structures from measurements of surface waves

    USGS Publications Warehouse

    Ryden, N.; Lowe, M.J.S.; Cawley, P.; Park, C.B.

    2006-01-01

    A method is presented for evaluating the thickness and stiffness of multilayered pavement structures from guided waves measured at the surface. Data is collected with a light hammer as the source and an accelerometer as receiver, generating a synthetic receiver array. The top layer properties are evaluated with a Lamb wave analysis. Multiple layers are evaluated by matching a theoretical phase velocity spectrum to the measured spectrum. So far the method has been applied to the testing of pavements, but it may also be applicable in other fields such as ultrasonic testing of coated materials. ?? 2006 American Institute of Physics.

  4. Impact of compressed natural gas fueled buses on street pavements

    SciTech Connect

    Yang, D.; Harrison, R.

    1995-07-01

    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.

  5. Graphene-based materials for flexible supercapacitors.

    PubMed

    Shao, Yuanlong; El-Kady, Maher F; Wang, Lisa J; Zhang, Qinghong; Li, Yaogang; Wang, Hongzhi; Mousavi, Mir F; Kaner, Richard B

    2015-05-26

    The demand for flexible/wearable electronic devices that have aesthetic appeal and multi-functionality has stimulated the rapid development of flexible supercapacitors with enhanced electrochemical performance and mechanical flexibility. After a brief introduction to flexible supercapacitors, we summarize current progress made with graphene-based electrodes. Two recently proposed prototypes for flexible supercapacitors, known as micro-supercapacitors and fiber-type supercapacitors, are then discussed. We also present our perspective on the development of graphene-based electrodes for flexible supercapacitors. PMID:25898904

  6. Flexible MIPS Soft Processor Architecture

    E-print Network

    Carli, Roberto

    2008-06-16

    The flexible MIPS soft processor architecture borrows selected technologies from high-performance computing to deliver a modular, highly customizable CPU targeted towards FPGA implementations for embedded systems; the ...

  7. Flexible MIPS soft processor architecture

    E-print Network

    Carli, Roberto

    2008-01-01

    The flexible MIPS soft processor architecture borrows selected technologies from high-performance computing to deliver a modular, highly customizable CPU targeted towards FPGA implementations for embedded systems; the ...

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

    SciTech Connect

    Synder, M.B.

    1995-03-01

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

  9. Feasibility of using 100% Recycled Asphalt Pavement mixtures for road construction

    NASA Astrophysics Data System (ADS)

    Carlson, Russell Edgar, IV

    Recycled Asphalt Pavement (RAP) is the largest recycled good in the United States and 80 million tons are recycled yearly, saving taxpayers about $1.5 billion dollars. This paper explores the possibility of utilizing 100% RAP materials in asphalt pavement. Asphalt mixtures are produced at 135°C in a typical asphalt plant. However, at 135°C, not all binder from RAP materials may not become effective for coating aggregates. The main objective of the study is to determine the amount of effective binder available from RAP in the asphalt plant. The 100% RAP mixes have aged binder that can alter mix designs and interaction with virgin binder. In this study, to determine low temperature cracking resistance and fatigue performance, samples were prepared using a 100% RAP mix with no virgin binder and a 100% RAP mix with virgin asphalt binder to achieve the optimum binder content of the mix. Second, to determine the effectiveness of binder from RAP materials, compaction tests were performed by heating RAP materials at various temperatures. It was found that 100% RAP mixes cannot be feasible for field use if additional virgin binder is added to reach the optimum asphalt content. Based on limited test results, the low temperature grade was not within proper limits but the beam fatigue testing results were acceptable. Based on compaction test results, additional heating is needed to increase the effectiveness of asphalt binder from RAP materials.

  10. Individual inconsistencies in basal and summit metabolic rate highlight flexibility of metabolic performance in a wintering passerine.

    PubMed

    Cortés, Pablo Andrés; Petit, Magali; Lewden, Agnès; Milbergue, Myriam; Vézina, François

    2015-03-01

    Resident passerines inhabiting high latitude environments are faced with strong seasonal changes in thermal conditions and energy availability. Summit metabolic rate (maximal metabolic rate elicited by shivering during cold exposure: M(sum)) and basal metabolic rate (BMR) vary in parallel among seasons and increase in winter due to cold acclimatization, and these adjustments are thought to be critical for survival. Wintering individuals expressing consistently higher M(sum) and BMR could therefore be seen as better performers with higher chances of winter survival than those exhibiting lower metabolic performance. In this study, we calculated repeatability to evaluate temporal consistency of body mass, BMR and M(sum) within and across three consecutives winters in black-capped chickadees (Poecile atricapillus). We found that body mass was significantly repeatable both within and across winters (R 0.51-0.90). BMR (R 0.29-0.47) was only repeatable within winter while M(sum) was repeatable both among (R 0.33-0.49) and within winters (R 0.33-0.49) with the magnitude and significance of repeatability in both variables depending on the year and whether they were corrected for body mass or body size. The patterns of repeatability observed among years also differed between the two variables. Our findings suggest that the relative ranking of individuals in winter metabolic performance is affected by local ecological conditions and can change within relatively short periods of time. PMID:25690265

  11. Sterile disposable sheath system for flexible cystoscopes

    Microsoft Academic Search

    Nathan Lawrentschuk; Michael Chamberlain

    2005-01-01

    Flexible cystourethroscopy is an accepted routine procedure in urology. The sterilization of instruments is time consuming and may damage flexible instruments. However, it must be performed to prevent contamination of the endoscopes. This study is the first to document experience using a flexible cystoscope with a disposable sheath in a urologic setting.

  12. Laboratory evaluation of microwave-heated asphalt pavement materials

    Microsoft Academic Search

    Al-Ohaly

    1987-01-01

    The potential use of microwave energy to heat asphalt mixtures and pavements has begun attracting attention. Microwave heating is rapid, deep and uniform. With microwaves, heat is generated by the treated material under the excitation of an alternating electromagnetic field caused by the passing microwaves. Some materials such as water heat very well with microwaves, while others such as Teflon

  13. Exploration of Pavement Oxidation Model Applications and Field Validation

    E-print Network

    Cui, Yuanchen

    2014-08-11

    model and validated their accuracies by field data, including one complicated case, a layer-by-layer prediction on a seal coat treated pavement. To better understand the asphalt aging process, the last topic in this dissertation was to study a dynamic...

  14. COLORADO DEPARTMENT OF TRANSPORTATION Sustainability of Concrete Pavement

    E-print Network

    · 2 Mile Reconstruction Existing: · 4 Lane Divided Highway · 8" Concrete Pavement (Recycled on-site) · 4" Asphalt Overlay (Recycled off-site) Project Design: · 6 Lane Divided Highway · 13" Concrete Modifications · Original Detour 12" Asphalt · Approved Detour 7" Concrete (Recycled on-site) Award · ACPA's 2011

  15. EVALUATION AND MITIGATION OF ASPHALT PAVEMENT TOP-DOWN CRACKING

    Microsoft Academic Search

    John J. Emery

    Top-down cracking has become an asphalt surface course distress of growing concern that must be dealt with during the design, construction, maintenance, and resurfacing of long-life asphalt pavements. The surface course is designed for heavy vehicle loadings and general traffic conditions in terms of rutting, resistance, durability, noise levels, smoothness, and frictional characteristics. The surface course must be properly maintained

  16. Salt Frost Deterioration in Concrete Pavement --Causes and Mitigation

    E-print Network

    Salt Frost Deterioration in Concrete Pavement --Causes and Mitigation Zhichao Liu, Will Hansen and special effects such as surface tension and osmotic effect (salt solution). ·Below the nucleation the surface contains a salt solution, pore suction attracts surface liquid and additional ice growth may

  17. Life-cycle assessment of pavements. Part I: Critical review

    Microsoft Academic Search

    Nicholas J. Santero; Eric Masanet; Arpad Horvath

    2011-01-01

    The rapidly expanding set of pavement life-cycle assessments (LCAs) available in the literature represents the growing interest in improving the sustainability of this critical infrastructure system. The existing literature establishes a foundational framework for quantifying environmental impact, but fails to deliver global conclusions regarding materials choices, maintenance strategies, design lives, and other best-practice policies for achieving sustainability goals. In order

  18. Prediction of Wet-Pavement Skid Resistance and Hydroplaning Potential

    Microsoft Academic Search

    Ghim Ping Ong; T F Fwa

    2007-01-01

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

  19. Deteriorated pavements due to the alkali–silica reaction

    Microsoft Academic Search

    S. A Marfil; P. J Maiza

    2001-01-01

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

  20. Desert pavement morphology and dynamics, Big Bend National Park, Texas 

    E-print Network

    Harmon, Courtney Michelle

    2009-05-15

    Desert pavements consist of a one- to two-layer thick surface armory of stones overlying finer, virtually stone-free material which often adopts the appearance of a meticulously tiled mosaic. They cover half of the arid land surface in North America...

  1. Evaluation of Concrete Pavement Repair Using Precast Technology in Virginia

    Microsoft Academic Search

    Shabbir Hossain; Celik Ozyildirim

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

  2. In-pavement wireless sensor network for vehicle classification

    Microsoft Academic Search

    Ravneet Bajwa; Ram Rajagopal; Pravin Varaiya; Robert Kavaler

    2011-01-01

    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

  3. Concrete Pavement Research Project Title Project Description First Last Email

    E-print Network

    recommendations for materials selection, mix design and construction practices Dave Smiley SmileyD@michi gan) and the air-void system and how it affects the F-T durability of concrete. Design and conduct a phasedState Concrete Pavement Research Project Title Project Description First Last Email Date started

  4. Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates.

    PubMed

    Bryer, Pamela J; Scoggins, Mateo; McClintock, Nancy L

    2010-05-01

    Non-point-source pollution is a major source of ecological impairment in urban stream systems. Recent work suggests that coal-tar pavement sealants, used extensively to protect parking areas, may be contributing a large portion of the polycyclic aromatic hydrocarbon (PAH) loading seen in urban stream sediments. The hypothesis that dried coal-tar pavement sealant flake could alter the macroinvertebrate communities native to streams in Austin, TX was tested using a controlled outdoor laboratory type approach. The treatment groups were: control, low, medium, and high with total PAH concentrations (TPAH = sum of 16 EPA priority pollutant PAHs) of 0.1, 7.5, 18.4, & 300 mg/kg respectively. The low, medium, and high treatments were created via the addition of dried coal-tar pavement sealant to a sterile soil. At the start of the 24-day exposure, sediment from a minimally impacted local reference site containing a community of live sediment-dwelling benthic macroinvertebrates was added to each replicate. An exposure-dependent response was found for several stream health measures and for several individual taxa. There were community differences in abundance (P = 0.0004) and richness (P < 0.0001) between treatments in addition to specific taxa responses, displaying a clear negative relationship with the amount of coal-tar sealant flake. These results support the hypothesis that coal-tar pavement sealants contain bioavailable PAHs that may harm aquatic environments. PMID:19913343

  5. 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...

  6. OVERLAYSSustainable Solutions for Resurfacing and Rehabilitating Existing Pavements THIRD EDITION

    E-print Network

    Pavements May 2014 THIRD EDITION ACPA publicationTB021.03P #12;On the Cover source:Todd Hanson, Iowa DOT Merryman, Iowa DOT source:TheTranstec Group source:Todd Hanson, Iowa DOT #12;Technical Report Documentation Amanda Bordelon, PhD, University of Utah James Cable, PhD, P.E., Cable Concrete Consultation LC Dan De

  7. Horizontal cracking of continuously reinforced concrete pavement under environmental loadings

    Microsoft Academic Search

    Seongcheol Choi; Soojun Ha; Moon C. Won

    2011-01-01

    The objective of this study is to identify the mechanisms and associated variables of horizontal cracking in continuously reinforced concrete pavement (CRCP) and to develop mitigation methodologies. To this end, the laboratory and field testing were carried out. The behavior of CRCP at relatively early ages under environmental loadings was measured and compared with numerical analysis. The effect of factors

  8. 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...

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

    NASA Astrophysics Data System (ADS)

    Tapia Gutierrez, Patricio Enrique

    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.

  10. Flexible nanovectors

    NASA Astrophysics Data System (ADS)

    Pugno, Nicola M.

    2008-11-01

    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.

  11. Performance of an aircraft tire under cyclic braking and of a currently operational antiskid braking system

    NASA Technical Reports Server (NTRS)

    Tanner, J. A.

    1972-01-01

    An experimental investigation was conducted to study the performance of an aircraft tire under cyclic braking conditions and to study the performance of a currently operational aircraft antiskid braking system. Dry, damp, and flooded runway surface conditions were used in the investigation. The results indicated that under cyclic braking conditions the braking and cornering-force friction coefficients may be influenced by fluctuations in the vertical load, flexibility in the wheel support, and the spring coupling between the wheel and the tire-pavement interface. The cornering capability was shown to be negligible at wheel slip ratios well below a locked-wheel skid under all test surface conditions. The maximum available brake-force friction coefficient was shown to be dependent upon the runway surface condition, upon velocity, and, for wet runways, upon tire differences. Moderate reductions in vertical load and brake system pressure did not significantly affect the overall wet-runway performance of the tire.

  12. Laboratory analysis of the infiltration capacity of interlocking concrete block pavements in car parks.

    PubMed

    Sañudo-Fontaneda, Luis A; Rodriguez-Hernandez, Jorge; Vega-Zamanillo, Angel; Castro-Fresno, Daniel

    2013-01-01

    Interlocking concrete block pavements (ICBPs) have been widely used in car parks to reduce runoff. Researches have demonstrated that clogging is the most influential factor in the reduction of the infiltration capacity of this type of permeable pavement. Nevertheless, there is no laboratory study of the infiltration performance of ICBPs that combines clogging levels with variables related with the topography of car parks such as runoff surface length (R(SL)) and surface slope (S(S)). This paper studies the infiltration behaviour of ICBP during their operational life in a car park using an improved version of the Cantabrian Fixed (CF) Infiltrometer. This laboratory device simulates direct rainfall and runoff from adjacent impervious areas over an ICBPs surface of 0.25 m(2) for different slopes (0, 3, 5, 7 and 10%) and three scenarios of clogging (surface newly built, surface clogged and surface clogged with maintenance). This paper presents the results of the tests and a statistical analysis based on three regression models (corresponding to each clogging scenario) depending on the R(SL) and S(S) variables. All models passed a confidence level of 95%, presenting high R(2) values and showing that R(SL) is a more influential variable than the S(S) for all clogging scenarios. PMID:23202575

  13. Enhancing the resolution of gpr spectra for pavement engineering applications

    NASA Astrophysics Data System (ADS)

    Benedetto, F.; Benedetto, A.

    2012-04-01

    Ground Penetrating Radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. This non-destructive method uses electromagnetic radiation and detects the reflected signals from subsurface structures. It can detect objects, changes in material, and voids and cracks. GPR has many applications in a number of fields. In the field of civil engineering one of the most advanced technologies used for road pavement monitoring is based on the deployment of advanced GPR systems. One of the most relevant causes of road pavement damage is often referable to water intrusion in structural layers. In this context, GPR has been recently proposed as a method to estimate moisture content in a porous medium without preventive calibration. Hence, the development of methods to obtain an estimate of the moisture content is a crucial research field involving economic, social and strategic aspects in road safety for a great number of public and private Agencies. In particular, a recent new approach was proposed to estimate moisture content in a porous medium basing on the theory of Rayleigh scattering, showing a shift of the frequency peak of the GPR spectrum towards lower frequencies as the moisture content increases in the soil. The weakness characterizing this approach is represented by the needs of high resolution signals, whereas GPR spectra are affected by low resolution. Hence, the rising requirement for high resolution leads to specific demands for improved prediction methods. Recently, a new technique combining the response of the conventional fast Fourier transform (FFT, well known for its high-precision receiving signal level) with that of the MUSIC (multiple signal classification) algorithm, well known for its super-resolution capacity has been proposed. This combined method has been proved to obtain a high precision level in quantifying the shift of the frequency peak of the GPR spectrum. This combined method can perform a reliable coarse estimate of the (abscissa of the) frequency peak. Unfortunately, whereas resolution affecting the GPR spectra has been enhanced, we still need a sensible increasing of the moisture content to appreciate a visible frequency shift. Hence, sub-sample resolution techniques are needed to obtain a resolution better than the sample period. Addressing some of these issues, this work proposes a sub-sample resolution technique exploiting a fast parabolic interpolator, running on three samples of the GPR spectrum in the neighborhood of the frequency peak (i.e. the coarse estimation). More in details, the new detector searches for the (abscissa of the) vertex of the parabola fitted over three GPR samples: the coarse estimate of the frequency peak, and one sample before and after this estimation. The rationale behind the new fast parabolic approach is as follows. We expect the method to obtain a finer estimation of the (abscissa of the) frequency peak because we are now interpolating a parabola in the neighborhood of the same maximum (i.e the coarse estimate), but with a narrow variance thus increasing the estimation accuracy. No noteworthy increase of computational complexity and processing throughput is required to implement the new approach. In fact, near the totality of the amount of the required computation is due to the former stage (i.e. FFT and/or MUSIC implementation to evaluate the coarse estimate of the frequency peak), and the latter logic (i.e. the interpolation function) is negligible from implementation and computational point of view. Experimental results confirm the effectiveness of the proposed approach to evidence and quantify moisture content in soil. In fact, the proposed sub-sample super resolution technique can resolve a frequency shift in the GPR spectrum even for a corresponding amount of moisture less than 2-3%.

  14. Robust SiO2-modified CoFe2O4 hollow nanofibers with flexible room temperature magnetic performance.

    PubMed

    Jing, Panpan; Pan, Lining; Du, Jinlu; Wang, Jianbo; Liu, Qingfang

    2015-05-01

    A range of robust SiO2-modified CoFe2O4 hollow nanofibers with high uniformity and productivity were successfully prepared via polyvinylpyrrolidone-sol assisted electrospinning followed by annealing at a high temperature of 1000 °C, and they were characterized using scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction and X-ray photoelectron spectroscopy in detail. It was demonstrated that amorphous SiO2 has a significant influence on not only the surface morphology, microstructure and crystalline size but also the room temperature magnetic performance of the inverse spinel CoFe2O4 nanofibers. The pure CoFe2O4 sample shows a particle chain rod-shape appearance but the SiO2-modified CoFe2O4 sample shows a robust hollow fibrous structure. With increasing SiO2 content, an increase at first and then a decrease in coercivity (Hc) and monotonously a decrease in saturation magnetization (Ms) have been determined in the obtained modified CoFe2O4 hollow nanofibers. A maximum Ms of about 80 emu g(-1) and a maximum Hc of about 1477 Oe could be, respectively, acquired from the pure CoFe2O4 nanorods and the modified CoFe2O4 hollow nanofibers with about 14.9% SiO2. The changes in Ms, Hc and the structure evolution mechanism of these SiO2-modified CoFe2O4 hollow nanofibers have been elaborated systematically. Furthermore, it is suggested that amorphous SiO2 enables effectively improving the structure endurance of 1D electrospun inorganic oxide hollow nanostructures being subjected to high temperatures. PMID:25907405

  15. Research on the characteristics of temperature field of asphalt pavement in seasonal frozen region

    NASA Astrophysics Data System (ADS)

    Qiao, Jiangang; Liu, Weizheng

    2014-08-01

    The characteristics of climate in seasonal frozen area are low temperature and a large range of temperature variation between day and night in winter. These characteristics often lead to problems of asphalt pavement, especially transverse cracks. To reduce the problems of asphalt pavement, it is necessary to examine the distribution of the temperature range of asphalt pavement. A three-dimensional finite element model was used, taking the SMA asphalt pavement as an example with solid70 and plane55 unit features of ANSYS software. It can obtain the relationship between temperature gradient and time and the relationship between temperature gradient and depth. In addition, a function relation model of stress and time was also established. It can provide a theoretical basis for the prevention and treatment of problems of asphalt pavement in seasonal frozen area. Moreover, it has an important significance for improving asphalt pavement design.

  16. Valuing flexibilities in the design of urban water management systems.

    PubMed

    Deng, Yinghan; Cardin, Michel-Alexandre; Babovic, Vladan; Santhanakrishnan, Deepak; Schmitter, Petra; Meshgi, Ali

    2013-12-15

    Climate change and rapid urbanization requires decision-makers to develop a long-term forward assessment on sustainable urban water management projects. This is further complicated by the difficulties of assessing sustainable designs and various design scenarios from an economic standpoint. A conventional valuation approach for urban water management projects, like Discounted Cash Flow (DCF) analysis, fails to incorporate uncertainties, such as amount of rainfall, unit cost of water, and other uncertainties associated with future changes in technological domains. Such approach also fails to include the value of flexibility, which enables managers to adapt and reconfigure systems over time as uncertainty unfolds. This work describes an integrated framework to value investments in urban water management systems under uncertainty. It also extends the conventional DCF analysis through explicit considerations of flexibility in systems design and management. The approach incorporates flexibility as intelligent decision-making mechanisms that enable systems to avoid future downside risks and increase opportunities for upside gains over a range of possible futures. A water catchment area in Singapore was chosen to assess the value of a flexible extension of standard drainage canals and a flexible deployment of a novel water catchment technology based on green roofs and porous pavements. Results show that integrating uncertainty and flexibility explicitly into the decision-making process can reduce initial capital expenditure, improve value for investment, and enable decision-makers to learn more about system requirements during the lifetime of the project. PMID:24268059

  17. Experimental studies of the dilution of vehicle exhaust pollutants by environment-protecting pervious pavement.

    PubMed

    Liu, Chung-Ming; Chen, Jui-Wen; Tsai, Jen-Hui; Lin, Wei-Shian; Yen, M-T; Chen, Ting-Hao

    2012-01-01

    This study determines whether environment-protecting pervious pavement can dilute pollutants immediately after emissions from vehicle. The turbulence-driven dry-deposition process is too slow to be considered in this aspect. The pavement used is the JW pavement (according to its inventors name), a high-load-bearing water-permeable pavement with patents in over 100 countries, which has already been used for more than 8 years in Taiwan and is well suited to replacing conventional road pavement, making the potential implementation of the study results feasible. The design of this study included two sets of experiments. Variation of the air pollutant concentrations within a fenced area over the JW pavement with one vehicle discharging emissions into was monitored and compared with results over a non-JW pavement. The ambient wind speed was low during the first experiment, and the results obtained were highly credible. It was found that the JW pavement diluted vehicle pollutant emissions near the ground surface by 40%-87% within 5 min of emission; whereas the data at 2 m height suggested that about 58%-97% of pollutants were trapped underneath the pavement 20 min after emission. Those quantitative estimations may be off by +/- 10%, if errors in emissions and measurements were considered. SO2 and CO2 underwent the most significant reduction. Very likely, pollutants were forced to move underneath due to the special design of the pavement. During the second experiment, ambient wind speeds were high and the results obtained had less credibility, but they did not disprove the pollutant dilution capacity of the JW pavement. In order to track the fate of pollutants, parts of the pavement were removed to reveal a micro version of wetland underneath, which could possibly hold the responsibility of absorbing and decomposing pollutants to forms harmless to the environment and human health. PMID:22393814

  18. TRUCK PERFORMANCE CURVES REFLECTIVE OF TRUCK AND PAVEMENT CHARACTERISTICS

    E-print Network

    Rakha, Hesham A.

    ABSTRACT The paper utilizes a linearly increasing variable power vehicle dynamics model to develop modeling, vehicle dynamics, roadway design, truck climbing lanes. INTRODUCTION Mannering and Kilareski

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    In this study, we report on the fabrication of high performance planar-type flexible micro-supercapacitor (MSC) arrays using Au electrodes coated with a functionalized multi-walled carbon nanotube (MWNT) film and a layer of MWNT-COOH/MnOx nanoparticle (NP) composite on top. The MWNT thin film was formed via layer-by-layer (LbL) assembly of MWNTs functionalized with amine groups and MWNTs with carboxylic acid groups in water. The hydrothermally synthesized composite of MWNT-COOH/MnOx NPs was coated on top of the MWNT film (LbL-MWNT). The addition of MWNT-COOH/MnOx NP composite as a top layer enhanced the performance of the MSCs dramatically, resulting in a volumetric capacitance of 50 F cm-3 at a scan rate of 10 mV s-1 and a coulombic efficiency of ~100%. By contrast, a volumetric capacitance of 3.6 F cm-3 was obtained when using only the LbL-MWNT film. After repetitive operation up to ~104 times, the capacitance remained at ~88.3% of the original value. With a deliberate circuit design consisting of serially connected MSC arrays, various light-emitting diodes operating at different bias voltages could be lit. The MSC circuit fabricated on a polyethylene terephthalate (PET) film showed stable electrochemical properties upon 1000 cycles of bending deformation.In this study, we report on the fabrication of high performance planar-type flexible micro-supercapacitor (MSC) arrays using Au electrodes coated with a functionalized multi-walled carbon nanotube (MWNT) film and a layer of MWNT-COOH/MnOx nanoparticle (NP) composite on top. The MWNT thin film was formed via layer-by-layer (LbL) assembly of MWNTs functionalized with amine groups and MWNTs with carboxylic acid groups in water. The hydrothermally synthesized composite of MWNT-COOH/MnOx NPs was coated on top of the MWNT film (LbL-MWNT). The addition of MWNT-COOH/MnOx NP composite as a top layer enhanced the performance of the MSCs dramatically, resulting in a volumetric capacitance of 50 F cm-3 at a scan rate of 10 mV s-1 and a coulombic efficiency of ~100%. By contrast, a volumetric capacitance of 3.6 F cm-3 was obtained when using only the LbL-MWNT film. After repetitive operation up to ~104 times, the capacitance remained at ~88.3% of the original value. With a deliberate circuit design consisting of serially connected MSC arrays, various light-emitting diodes operating at different bias voltages could be lit. The MSC circuit fabricated on a polyethylene terephthalate (PET) film showed stable electrochemical properties upon 1000 cycles of bending deformation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02035a

  20. Flexible rotor dynamics analysis

    NASA Technical Reports Server (NTRS)

    Shen, F. A.

    1973-01-01

    A digital computer program was developed to analyze the general nonaxisymmetric and nonsynchronous transient and steady-state rotor dynamic performance of a bending- and shear-wise flexible rotor-bearing system under various operating conditions. The effects of rotor material mechanical hysteresis, rotor torsion flexibility, transverse effects of rotor axial and torsional loading and the anisotropic, in-phase and out-of-phase bearing stiffness and damping force and moment coefficients were included in the program to broaden its capability. An optimum solution method was found and incorporated in the computer program. Computer simulation of experimental data was made and qualitative agreements observed. The mathematical formulations, computer program verification, test data simulation, and user instruction was presented and discussed.

  1. Flexible Electronics: What can it do? What should it do?

    Microsoft Academic Search

    Sameer M. Venugopal; David R. Allee; Manuel Quevedo-Lopez; Bruce Gnade; Eric Forsythe; David Morton

    2010-01-01

    The development of low temperature, thin film transistor processes that has enabled flexible displays also presents opportunities for flexible electronics. A variety of flexible digital and analog electronics have been demonstrated, although typically of modest performance. We review the state-of-the-art in flexible electronics followed by a discussion of the constraints, remaining challenges and realistic potential applications of thin film transistors

  2. Contributions to an Improved Oxygen and Thermal Transport Model and Development of Fatigue Analysis Software for Asphalt Pavements 

    E-print Network

    Jin, Xin

    2012-02-14

    Fatigue cracking is one primary distress in asphalt pavements, dominant especially in later years of service. Prediction of mixture fatigue resistance is critical for various applications, e.g., pavement design and ...

  3. Development of a mult-objective strategic management approach to improve decisions for pavement management practices in local agencies 

    E-print Network

    Chang Albitres, Carlos Martin

    2009-05-15

    limited. This research develops a multi-objective strategic management approach oriented to improving decisions for pavement management practices in local agencies. In this approach, target objectives are tied to key pavement network parameters...

  4. High-performance, highly bendable MoS2 transistors with high-k dielectrics for flexible low-power systems.

    PubMed

    Chang, Hsiao-Yu; Yang, Shixuan; Lee, Jongho; Tao, Li; Hwang, Wan-Sik; Jena, Debdeep; Lu, Nanshu; Akinwande, Deji

    2013-06-25

    While there has been increasing studies of MoS2 and other two-dimensional (2D) semiconducting dichalcogenides on hard conventional substrates, experimental or analytical studies on flexible substrates has been very limited so far, even though these 2D crystals are understood to have greater prospects for flexible smart systems. In this article, we report detailed studies of MoS2 transistors on industrial plastic sheets. Transistor characteristics afford more than 100x improvement in the ON/OFF current ratio and 4x enhancement in mobility compared to previous flexible MoS2 devices. Mechanical studies reveal robust electronic properties down to a bending radius of 1 mm which is comparable to previous reports for flexible graphene transistors. Experimental investigation identifies that crack formation in the dielectric is the responsible failure mechanism demonstrating that the mechanical properties of the dielectric layer is critical for realizing flexible electronics that can accommodate high strain. Our uniaxial tensile tests have revealed that atomic-layer-deposited HfO2 and Al2O3 films have very similar crack onset strain. However, crack propagation is slower in HfO2 dielectric compared to Al2O3 dielectric, suggesting a subcritical fracture mechanism in the thin oxide films. Rigorous mechanics modeling provides guidance for achieving flexible MoS2 transistors that are reliable at sub-mm bending radius. PMID:23668386

  5. Vehicle classes for pavement design and capacity analysis

    SciTech Connect

    Kubala, J.; Asce, M.; Lalani, N.; O'Connell, R.; Petersen, C.

    1986-11-01

    Transportation engineers working in Colorado were aware of a lack of published data at both the local and national level for vehicle classes on urban streets. Such vehicle class breakdowns are necessary for calculating equivalent daily loaded axle (EDLA) values for pavement design and conducting capacity analyses. A technical committee was formed to collect and analyze weekday vehicle class data on urban streets of various types. The major vehicle classes are passenger cars (70-75%), pickups (15-20%), single unit trucks (5-7%); tractor-trailers, buses, and recreational vehicles account for less than 1%. Using these data, a microcomputer spread sheet was set up to calculate EDLA values for pavement design for a range of design year volumes. This vehicle class data is also very useful in highway capacity calculations.

  6. PORTABLE SEISMIC ACQUISTION SYSTEM (PSAS) FOR PAVEMENT MASW

    Microsoft Academic Search

    Nils Ryden; Peter Ulriksen; Choon Park; Richard Miller

    A seismic method (e.g., surface- or body-wave method) has been often used in pavement engineering to evaluate such critical constructional parameters as the E-modulus and Poisson's ratio. Conventional method usually uses one or two-channel recording device (e.g., dynamic signal analyzer) for data acquisition whose cost is by no means trivial. In addition, recent appli- cations with the multichannel approach have

  7. Should we be gritting pavements to prevent pedestrian injuries?

    PubMed

    Atenstaedt, Rob; Rees, Michael

    2013-05-01

    Unintentional injuries are an important public health issue, and are a significant burden on health and social services, especially during the winter months. Dr Rob Atenstaedt, Consultant in Public Health Medicine, Public Health Wales & Honorary Senior Lecturer, Bangor University and Professor Michael Rees, University Director of Medical Development & Professor of Cardiovascular Studies, Bangor University look at the importance of pavement gritting in preventing injuries and falls in pedestrians. PMID:23657235

  8. The effects of traffic on a performance prediction model

    E-print Network

    Martin, Timothy James

    1995-01-01

    This thesis analyzes the use of different age and traffic combinations in determining the predicted condition of pavements. The purpose of this study is to develop improved performance prediction models using traffic data from cities and counties...

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

    E-print Network

    Kim, Yoo Hyun

    2012-07-16

    will assist STAs in carrying out a LCCA, with the reliable estimation of maintenance costs. This research also provides the research community with the first view and systematic estimation method that STAs can use to determine long-term maintenance costs...

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

    E-print Network

    Masad, Sanaa Ahmad

    2004-09-30

    model....................................................................................................................65 4.20 Total permanent deformation in section C using the AASHTO 2002 model. .....65 5.1 Percent change in IRI... for different thicknesses of the base layer at 8in HMA and 8 ksi subgrade................................................................................................82 5.2 Percent change in IRI at two different thicknesses of HMA and at two types...

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

    E-print Network

    Masad, Sanaa Ahmad

    2004-09-30

    model....................................................................................................................65 4.20 Total permanent deformation in section C using the AASHTO 2002 model. .....65 5.1 Percent change in IRI... for different thicknesses of the base layer at 8in HMA and 8 ksi subgrade................................................................................................82 5.2 Percent change in IRI at two different thicknesses of HMA and at two types...

  12. Quantifying Evaporation and Evaluating Runoff Estimation Methods in a Permeable Pavement System

    EPA Science Inventory

    The U.S. Environmental Protection Agency constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable pavement in the parking lanes which were designed to receive run-on from the impervious hot-mix asphalt driving lanes. Twelve lined permeable pavement sec...

  13. Video Conference Agenda and Meeting Notes: Two-Lift Concrete Pavements 27 June 2007

    E-print Network

    ­ especially in top lift of two-lift concrete. Recycled material use was big ­ another real potentialVideo Conference Agenda and Meeting Notes: Two-Lift Concrete Pavements 27 June 2007 Location: FHWA:10 am International Scan on Long Life Concrete Pavements Tom Cackler, Director National Concrete

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

    SciTech Connect

    NONE

    1995-03-01

    The bibliography contains citations concerning the recycling of asphalt pavement materials for road construction. Citations discuss asphalt concrete mixtures and recycling, recycled materials testing and evaluation, and pavement bases. Engineering and environmental aspects of recycled materials are examined. (Contains a minimum of 78 citations and includes a subject term index and title list.)

  15. The Edison Environmental Center Permeable Pavement Site: Initial Results from a Stormwater Control Designed for Monitoring

    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...

  16. Measurement of visibility loss due to splash and spray: porous, SMA and conventional asphalt pavements

    Microsoft Academic Search

    Pichaya Rungruangvirojn; Kunnawee Kanitpong

    2010-01-01

    Road traffic accidents are a major problem for the safety, well-being and economies of Southeast Asian countries. In Thailand, many accidents are caused by environmental or road conditions. Poor visibility on wet pavement is a major cause of accidents. Accumulated water on wet pavement surfaces creates the ‘splash and spray’ effect, resulting in visibility loss. The main objective of this

  17. A Laboratory Study on Reduction of the Heat Island Effect of Asphalt Pavements

    Microsoft Academic Search

    Bao-Liang Chen; Sankha Bhowmick; Rajib B. Mallick

    Heat islands are formed as a result of construction that replaces vegetation with absorptive surfaces. Air temperature rises as a result of formation of heat islands. One suggested method to reduce the emitted heat from asphalt pavement surfaces is to reduce the temperature of the surface by flowing a suitable fluid through the pavement. The heated fluid could then be

  18. Rating the Aircraft Load and Reporting the Bearing Capacity of Rigid Airport Pavements

    Microsoft Academic Search

    Andreas Loizos; George Charonitis; Petros Katsoulas

    2006-01-01

    Successful management of airport pavements presumes the existence of a suitable procedure for the structural classification and the continuous monitoring of their bearing capacity. According to the modern trend, it is necessary to utilise a pavement to the maximum extend without risking not only the safety of the flights but also the cost of economic penalties which might arise from

  19. Evaluation of innovative concepts relating to prestressed concrete pavements, volume 5

    NASA Astrophysics Data System (ADS)

    Ciolko, A. T.; Nussbaum, P. J.

    1983-06-01

    This report presents an evaluation of three methods for post-tensioning concrete pavements without embedded steel tendons. All methods permit joint movement while maintaining slab pre-stress at the pavement joint. One method consists of thin-wall hydraulically presurized bellows as stressing elements. The second uses a pnuematically charged rubber bladder. The third method makes use of stacked Belleville springs.

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

    ERIC Educational Resources Information Center

    Dave, Eshan V.

    2009-01-01

    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…